V8 SpiderMonkey JavaScriptCore Chakra Other
⬤ Minor difference (1 point) ⬤ Small feature (2 points) ⬤ Medium feature (4 points) ⬤ Large feature (8 points)
Compilers/polyfills Desktop browsers Servers/runtimes Mobile
Feature name Current browser Traceur Babel 6 +
core-js 2		 Babel 7 +
core-js 2		 Babel 7 +
core-js 3		 Closure 2020.09 Closure 2021.08 Closure 2021.09 Closure 2021.10 Closure 2021.11 Closure 2022.05 Closure 2022.07 Closure 2023.02 Type-
Script +
core-js 2		 Type-
Script +
core-js 3		 Type-
Script +
core-js 3		 Type-
Script +
core-js 3		 Type-
Script +
core-js 3		 Type-
Script +
core-js 3		 Type-
Script +
core-js 3		 TypeScript+
core-js 3		 es7-shim IE 11 FF 115 ESR FF 128 ESR FF 137 FF 138 FF 139 FF 140 ESR FF 141 FF 142 FF 143 FF 144 FF 145 FF 146 FF 147 FF 148 FF 149 FF 150 FF 151 FF 152 OP 12.10 CH 136 CH 137 CH 138 CH 139 CH 140 CH 141 CH 142 CH 143 CH 144 CH 145 CH 146 CH 147 CH 148 CH 149 Edge 136 Edge 137 Edge 138 Edge 139 Edge 140 Edge 141 Edge 142 Edge 143 Edge 144 Edge 145 Edge 146 Edge 148 SF 15.6 SF 17.5 SF 17.6 SF 18 SF 18.1 SF 18.2 SF 18.3 SF 18.4 SF 18.5 SF 18.6 SF 26 SF 26.1 SF 26.2 SF 26.3 SF 26.4 SF TP WK OP 102 OP 103 OP 104 OP 105 OP 106 OP 107 OP 108 OP 109 OP 110 OP 111 OP 112 Rhino 1.7.15 Rhino 1.8.0 Rhino 1.9.0 PJS Node >=18.3 <19 Node >=20 <21 Node >=22 <23 Node >=23 <24 Node >=24 Node >=25 DUK 2.6 DUK 2.7 JrS 2.3.0 JrS 2.4.0 JrS 3.0.0 GraalVM 19.3.1[3] GraalVM 19.3.6[3] GraalVM 20.0.0[3] GraalVM 20.1.0[3] GraalVM 20.3.0[3] GraalVM 20.3.1[3] GraalVM 21.0.0[3] GraalVM 21.3.3[4] GraalVM 22.2.0[4] GraalVM 25.0.1 Hermes 0.7.0 Hermes 0.12.0 Deno 1.33 Deno 1.34 Deno 1.35 Deno 1.36 AN 4.4 AN 4.4.3 iOS 12.2 iOS 13.4 iOS 14.5 iOS 16.6 iOS 17.0 iOS 17.1 iOS 17.2 iOS 17.3 iOS 17.4 iOS 17.5 iOS 17.6 iOS 18.0 iOS 26.0 Samsung 24 Samsung 25 Samsung 26 Samsung 27 Opera Mobile 72 Opera Mobile 73 Opera Mobile 74 Opera Mobile 75 Opera Mobile 76 Opera Mobile 77 React Native 0.70.3 (Hermes + Babel)
2016 features
§exponentiation (**) operator MDN (Mozilla Development Network) logo  2/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3 2/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3
§basic support Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§assignment Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§early syntax error for unary negation without parens ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Array.prototype.includes MDN (Mozilla Development Network) logo  0/4 4/4 4/4 4/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 3/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 3/4 4/4 4/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4
§Array.prototype.includes MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Array.prototype.includes handles sparse arrays MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Array.prototype.includes is generic ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§%TypedArray%.prototype.includes MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
2016 misc
§generator functions can't be used with "new" MDN (Mozilla Development Network) logo [7] ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§generator throw() caught by inner generator MDN (Mozilla Development Network) logo [8] ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§strict fn w/ non-strict non-simple params is error[10] ? ? ? Yes ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§nested rest destructuring, declarations MDN (Mozilla Development Network) logo [11] ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§nested rest destructuring, parameters[12] ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Proxy, "enumerate" handler removed MDN (Mozilla Development Network) logo [13] ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Proxy internal calls, Array.prototype.includes ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
2017 features
§Object static methods 0/4 4/4 4/4 4/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 3/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 3/4 4/4 4/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4
§Object.values MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Object.entries MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Object.getOwnPropertyDescriptors MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Object.getOwnPropertyDescriptors doesn't provide undefined descriptors ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§String padding 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2
§String.prototype.padStart MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§String.prototype.padEnd MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§trailing commas in function syntax MDN (Mozilla Development Network) logo  0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 1/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2
§in parameter lists MDN (Mozilla Development Network) logo  ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§in argument lists MDN (Mozilla Development Network) logo  ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§async functions MDN (Mozilla Development Network) logo  4/16 4/16 9/16 12/16 12/16 12/16 12/16 12/16 12/16 12/16 12/16 12/16 9/16 9/16 9/16 9/16 9/16 9/16 9/16 9/16 0/16 0/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 0/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 0/16 0/16 0/16 0/16 16/16 16/16 16/16 16/16 16/16 16/16 0/16 0/16 9/16 13/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 0/16 12/16 16/16 16/16 16/16 16/16 0/16 0/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 11/16
§return Yes Yes[14] Yes[14] Yes[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§throw ? ? Yes[14] Yes[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§no line break between async and function ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§no "prototype" property ? ? ? ? No No No No No No No No No No No No No No No No ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§await MDN (Mozilla Development Network) logo  Yes Yes[14] Yes[14] Yes[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§await, rejection ? ? Yes[14] Yes[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§must await a value ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§can await non-Promise values ? ? Yes[14] Yes[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§cannot await in parameters ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§async methods, object literals ? ? Yes[14] Yes[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§async methods, classes ? ? Yes[14] Yes[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§async arrow functions in methods, classes Yes Yes[14] Yes[14] Yes[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§async arrow functions Yes Yes[14] Yes[14] Yes[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§correct prototype chain ? ? ? ? No No No No No No No No No No No No No No No No ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§async function prototype, Symbol.toStringTag ? ? ? ? No No No No No No No No No No No No No No No No ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§async function constructor ? ? ? ? No No No No No No No No No No No No No No No No ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§shared memory and atomics 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 0/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 0/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 0/17 0/17 0/17 0/17 17/17 17/17 17/17 17/17 17/17 17/17 0/17 0/17 0/17 0/17 17/17 16/17 16/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 0/17 0/17 17/17 17/17 17/17 17/17 0/17 0/17 0/17 0/17 0/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 17/17 0/17
§SharedArrayBuffer MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§SharedArrayBuffer[Symbol.species] ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§SharedArrayBuffer.prototype.byteLength MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§SharedArrayBuffer.prototype.slice MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§SharedArrayBuffer.prototype[Symbol.toStringTag] ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.add MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.and MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.compareExchange MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.exchange MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.wait MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.notify MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes No No Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.isLockFree MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.load MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.or MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.store MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.sub MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Atomics.xor MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No[16] No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
2017 misc
§RegExp "u" flag, case folding ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§arguments.caller removed MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes ? Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
2017 annex b
§Object.prototype getter/setter methods 0/16 16/16 16/16 16/16 0/16 0/16 0/16 0/16 0/16 0/16 0/16 0/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 0/16 8/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 12/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 10/16 10/16 10/16 12/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 0/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 6/16 6/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16 16/16
§__defineGetter__ MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__defineGetter__, symbols ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Flag[17] Flag[17] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__defineGetter__, ToObject(this) ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__defineSetter__ MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__defineSetter__, symbols ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Flag[17] Flag[17] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__defineSetter__, ToObject(this) ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupGetter__ MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupGetter__, prototype chain ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupGetter__, symbols ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Flag[17] Flag[17] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupGetter__, ToObject(this) ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupGetter__, data properties can shadow accessors ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupSetter__ MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupSetter__, prototype chain ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupSetter__, symbols ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Flag[17] Flag[17] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupSetter__, ToObject(this) ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupSetter__, data properties can shadow accessors ? Yes[5] Yes[5] Yes[5] ? ? ? ? ? ? ? ? Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Proxy internal calls, getter/setter methods 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4
§__defineGetter__ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__defineSetter__ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupGetter__ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§__lookupSetter__ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§assignments allowed in for-in head in non-strict mode MDN (Mozilla Development Network) logo  Yes ? ? Yes ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
2018 features
§object rest/spread properties 0/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 1/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2
§object rest properties ? Yes Yes Yes No[18] No[18] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§object spread properties ? Yes Yes Yes No[18] No[18] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Promise.prototype.finally MDN (Mozilla Development Network) logo  0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3
§basic support ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§don't change resolution value ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§change rejection value ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§s (dotAll) flag for regular expressions MDN (Mozilla Development Network) logo  ? Yes Yes Yes No No No No No No No No ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§RegExp named capture groups MDN (Mozilla Development Network) logo  ? Yes Yes Yes ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes ? Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§RegExp Lookbehind Assertions MDN (Mozilla Development Network) logo  ? ? ? No ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes ? Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§RegExp Unicode Property Escapes MDN (Mozilla Development Network) logo  0/10 1/10 1/10 1/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 0/10 7/10 7/10 9/10 9/10 9/10 9/10 9/10 9/10 9/10 9/10 9/10 9/10 10/10 10/10 10/10 10/10 10/10 10/10 0/10 8/10 8/10 8/10 8/10 8/10 8/10 8/10 8/10 8/10 9/10 9/10 9/10 9/10 9/10 8/10 8/10 8/10 8/10 8/10 8/10 8/10 8/10 8/10 9/10 9/10 9/10 6/10 7/10 7/10 8/10 8/10 8/10 8/10 9/10 9/10 9/10 9/10 9/10 9/10 9/10 10/10 9/10 9/10 7/10 7/10 7/10 7/10 7/10 7/10 7/10 7/10 7/10 8/10 8/10 0/10 0/10 2/10 0/10 6/10 7/10 8/10 8/10 8/10 8/10 0/10 0/10 0/10 0/10 0/10 1/10 1/10 1/10 1/10 1/10 1/10 1/10 5/10 6/10 9/10 0/10 0/10 7/10 7/10 7/10 7/10 0/10 0/10 1/10 1/10 5/10 6/10 7/10 7/10 7/10 7/10 7/10 7/10 7/10 8/10 9/10 7/10 7/10 7/10 8/10 6/10 6/10 7/10 7/10 7/10 7/10 1/10
§basic ? Yes Yes Yes ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes ? Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Unicode 11 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No No ? ? ? ? ? ? ? Yes Yes Yes No No Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ?
§Unicode 12 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No No ? ? ? ? ? ? ? Yes Yes Yes No No Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ?
§Unicode 12.1 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes ? Yes Yes Yes Yes Yes Yes No No No No No ? ? ? ? ? ? ? Yes Yes Yes No No Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ?
§Unicode 13 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No No ? ? ? ? ? ? ? Yes Yes Yes No No Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ?
§Unicode 14 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No No ? ? ? ? ? ? ? No Yes Yes No No Yes Yes Yes Yes ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ?
§Unicode 15 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? No Yes Yes Yes Yes Yes No No No No No ? ? ? ? ? ? ? No No Yes No No Yes Yes Yes Yes ? ? No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes ?
§Unicode 15.1 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No ? No No No No No No No No Yes Yes No No No ? ? No Yes Yes Yes Yes No No No No No ? ? ? ? ? ? ? No No Yes No No ? ? ? ? ? ? No No No No No No No No No No No Yes Yes No No No Yes ? ? ? ? ? ? ?
§Unicode 16.0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No No No No No No No No No Yes Yes Yes Yes Yes No No No No No No No No No Yes Yes Yes ? ? No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? ? ? ? No No ? ? ? No No No No ? ? ? ? No ? ? ? ? ? ? ? No No Yes ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No No Yes ? ? ? ? ? ? ? ? ? ? ?
§Unicode 17.0 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes ? ? ? ? ? No No No No No No No No No No ? ? ? ? No No No No No No No No ? ? ? ? ? ? ? ? No No No No No No Yes Yes Yes ? ? ? ? ? ? ? ? ? ? ? ? ? No ? ? ? ? ? No No ? ? ? ? ? ? ? ? ? ? ? ? No No No ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No ? ? ? ? ? ? ? ? ? ? ?
§Asynchronous Iterators 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2
§async generators ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§for-await-of loops MDN (Mozilla Development Network) logo  ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
2018 misc
§Proxy "ownKeys" handler, duplicate keys for non-extensible targets MDN (Mozilla Development Network) logo  ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§template literal revision ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
2019 features
§Symbol.prototype.description MDN (Mozilla Development Network) logo  0/3 0/3 0/3 3/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 3/3 3/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 2/3 3/3 3/3 3/3 3/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3
§basic ? No No Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§empty description ? No No Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§undefined description ? No No Yes[5] ? ? ? ? ? ? ? ? ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Object.fromEntries MDN (Mozilla Development Network) logo  ? No No Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§string trimming 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 2/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 2/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 2/4 2/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4
§String.prototype.trimLeft MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§String.prototype.trimRight MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§String.prototype.trimStart MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§String.prototype.trimEnd MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Array.prototype.{flat, flatMap}[20] 0/3 1/3 1/3 3/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 1/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3 3/3 3/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3 2/3 3/3 3/3 3/3 3/3 0/3 0/3 2/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3
§Array.prototype.flat MDN (Mozilla Development Network) logo  ? No No Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Array.prototype.flatMap MDN (Mozilla Development Network) logo  ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§flat and flatMap in Array.prototype[@@unscopables] ? No No Yes[5] ? ? ? ? ? ? ? ? ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
2019 misc
§optional catch binding 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3 2/3 2/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 0/3 3/3 3/3 2/3 2/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 2/3 3/3 3/3 3/3 3/3 3/3 0/3 0/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3
§basic ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§await ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§yield ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Function.prototype.toString revision MDN (Mozilla Development Network) logo  0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 1/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 1/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 4/7 6/7 6/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 1/7 3/7 3/7 1/7 7/7 7/7 7/7 7/7 7/7 7/7 1/7 1/7 0/7 0/7 3/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 1/7 1/7 7/7 7/7 7/7 7/7 0/7 0/7 4/7 4/7 4/7 4/7 6/7 6/7 6/7 6/7 6/7 6/7 6/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 1/7
§functions created with the Function constructor ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§arrows ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§[native code] ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§class expression with implicit constructor ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§class expression with explicit constructor ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§unicode escape sequences in identifiers ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§methods and computed property names ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§JSON superset 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2
§LINE SEPARATOR can appear in string literals ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§PARAGRAPH SEPARATOR can appear in string literals ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Well-formed JSON.stringify MDN (Mozilla Development Network) logo  ? No No Yes[5] ? ? ? ? ? ? ? ? ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes No Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
2020 features
§String.prototype.matchAll MDN (Mozilla Development Network) logo  0/2 1/2 1/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 1/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 2/2 2/2 1/2 1/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2
§basic functionality ? Yes[5] Yes[5] Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Flag[21] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§throws on non-global regex ? No No Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes No No Flag[21] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§BigInt MDN (Mozilla Development Network) logo  0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 0/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 0/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 4/8 4/8 6/8 0/8 8/8 8/8 8/8 8/8 8/8 8/8 0/8 0/8 0/8 6/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 0/8 8/8 8/8 8/8 8/8 8/8 0/8 0/8 0/8 0/8 4/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8 8/8
§basic functionality ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§constructor ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§BigInt.asUintN ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§BigInt.asIntN ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§BigInt64Array ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§BigUint64Array ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§DataView.prototype.getBigInt64 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§DataView.prototype.getBigUint64 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Promise.allSettled MDN (Mozilla Development Network) logo  ? No No Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes No No Flag[21] Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§globalThis MDN (Mozilla Development Network) logo  0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2
§"globalThis" global property is global object ? No No Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§"globalThis" global property has correct property descriptor ? No No Yes[5] Yes Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§optional chaining operator (?.) MDN (Mozilla Development Network) logo  0/5 0/5 4/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 4/5 4/5 4/5 4/5 4/5 4/5 4/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 4/5 4/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 5/5 0/5 0/5 0/5 4/5 4/5 4/5 4/5 5/5 5/5 5/5 4/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5
§optional property access ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No Yes No No Flag[21] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§optional bracket access ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No Yes No No Flag[21] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§optional method call ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No Yes No No Flag[21] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§optional function call ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No Yes No No Flag[21] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§spread parameters after optional chaining ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No ? ? Yes ? ? ? ? ? ? ? Yes Yes Yes No Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§nullish coalescing operator (??) MDN (Mozilla Development Network) logo  ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes No No Flag[21] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
2021 features
§String.prototype.replaceAll MDN (Mozilla Development Network) logo  ? No No Yes[5] No Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes No No No Yes Yes No No Flag[21] Flag[22] Flag[22] Flag[22] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§Promise.any MDN (Mozilla Development Network) logo  0/2 0/2 0/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2
§fulfillment ? No No Yes[5] No Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No Yes ? ? ? ? Flag[22] Flag[22] Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§AggregateError ? No No Yes[5] No Yes Yes Yes Yes Yes Yes Yes ?[19] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] Yes[6] ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes ? Yes Yes Yes Yes Yes Yes No No No No Yes ? ? ? ? Flag[22] Flag[22] Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§WeakReferences MDN (Mozilla Development Network) logo  0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 1/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 0/2 0/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2
§WeakRef minimal support ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No Yes No No Flag[22] Flag[22] Flag[22] Flag[22] Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§FinalizationRegistry minimal support ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No ? Yes Yes Yes Yes Yes Yes No No No No No No No No No Flag[22] Flag[22] Yes Yes Yes Yes No No Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No
§Logical Assignment 0/9 0/9 9/9 9/9 0/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 0/9 0/9 0/9 0/9 0/9 0/9 0/9 0/9 0/9 0/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 0/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 0/9 6/9 6/9 0/9 9/9 9/9 9/9 9/9 9/9 9/9 0/9 0/9 0/9 0/9 9/9 0/9 0/9 0/9 0/9 0/9 0/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 0/9 0/9 0/9 0/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9