Lint CSS for browser support against Can I use database.

Install

npm install -g doiuse

Usage Examples

Command Line

doiuse --browsers "ie >= 9, > 1%, last 2 versions" main.css
# or
cat main.css | doiuse --browsers "ie >= 9, > 1%, last 2 versions"

Sample output:

/projects/website/main.css:5:3: CSS3 Box-sizing not supported by: IE (8-11), Chrome (36-38), Safari (8,7.1), Opera (24-25), iOS Safari (8,7.1,8.1), Android Browser (4.1,4.4,4.4.4), IE Mobile (10-11)
/projects/website/main.css:6:3: CSS3 Box-sizing not supported by: IE (8-11), Chrome (36-38), Safari (8,7.1), Opera (24-25), iOS Safari (8,7.1,8.1), Android Browser (4.1,4.4,4.4.4), IE Mobile (10-11)
/projects/website/main.css:8:3: CSS user-select: none not supported by: IE (8-9)
/projects/website/main.css:9:3: CSS user-select: none not supported by: IE (8-9)
/projects/website/main.css:10:3: CSS user-select: none not supported by: IE (8-9)
/projects/website/main.css:11:3: CSS user-select: none not supported by: IE (8-9)
/projects/website/main.css:12:3: CSS user-select: none not supported by: IE (8-9)
/projects/website/main.css:13:3: Pointer events not supported by: IE (8-10), Firefox (32-33), Chrome (36-38), Safari (8,7.1), Opera (24-25), iOS Safari (8,7.1,8.1), Android Browser (4.1,4.4,4.4.4), IE Mobile (10)
/projects/website/main.css:14:3: Pointer events not supported by: IE (8-10), Firefox (32-33), Chrome (36-38), Safari (8,7.1), Opera (24-25), iOS Safari (8,7.1,8.1), Android Browser (4.1,4.4,4.4.4), IE Mobile (10)
/projects/website/main.css:32:3: CSS3 Transforms not supported by: IE (8)

Use --json to get output as (newline-delimited) JSON objects.

JS

import postcss from 'postcss';
import DoIUse from 'doiuse/lib/DoIUse.js';
postcss(new DoIUse({
  browsers:['ie >= 6', '> 1%'],
  ignore: ['rem'], // an optional array of features to ignore
  ignoreFiles: ['**/normalize.css'], // an optional array of file globs to match against original source file path, to ignore
  onFeatureUsage: (usageInfo) => {
    console.log(usageInfo.message);
  }
})).process("a { background-size: cover; }")

CommonJS syntax is still supported if using var doiuse = require('doiuse').

Gulp (CommonJS)

var gulp = require('gulp')
var postcss = require('postcss')
var doiuse = require('doiuse')
gulp.src(src, { cwd: process.cwd() })
.pipe(gulp.postcss([
  doiuse({
    browsers: [
      'ie >= 8',
      '> 1%'
    ],
    ignore: ['rem'], // an optional array of features to ignore
    ignoreFiles: ['**/normalize.css'], // an optional array of file globs to match against original source file path, to ignore
    onFeatureUsage: function (usageInfo) {
      console.log(usageInfo.message)
    }
  })
]))

How it works

In particular, the approach to detecting features usage is currently quite naive.

Refer to the data in /data/features.js.

If a feature in that dataset only specifies properties, we just use those properties for regex/substring matches against the properties used in the input CSS.
If a feature also specifies values, then we also require that the associated value matches one of those values.

API Details

As a transform stream

var doiuse = require('doiuse/stream');
process.stdin
  .pipe(doiuse({ browsers: ['ie >= 8', '> 1%'], ignore: ['rem'] }))
  .on('data', function (usageInfo) {
    console.log(JSON.stringify(usageInfo))
  })

Yields UsageInfo objects as described below.

As a postcss plugin

postcss(new DoIUse(opts)).process(css), where opts is:

{
  browsers: ['ie >= 8', '> 1%'], // an autoprefixer-like array of browsers.
  ignore: ['rem'], // an optional array of features to ignore
  ignoreFiles: ['**/normalize.css'], // an optional array of file globs to match against original source file path, to ignore
  onFeatureUsage: function(usageInfo) { } // a callback for usages of features not supported by the selected browsers
}

And usageInfo looks like this:

{
  message: '<input source>: line <l>, col <c> - CSS3 Gradients not supported by: IE (8)',
  feature: 'css-gradients', // slug identifying a caniuse-db feature
  featureData: {
    title: 'CSS Gradients',
    missing: "IE (8)", // string of browsers missing support for this feature.
    missingData: {
      // map of browser -> version -> (lack of)support code
      ie: { '8': 'n' }
    },
    caniuseData: { // data from caniuse-db/features-json/[feature].json }
  },
  usage: {} //the postcss node where that feature is being used.
}

Called once for each usage of each css feature not supported by the selected browsers.

Ignoring file-specific rules

For disabling some checks you can use just-in-place comments

`/* doiuse-disable */`

Disables checks of all features

`/* doiuse-disable feature */`

Disables checks of specified feature(s) (can be comma separated list)

`/* doiuse-enable */`

Re-enables checks of all features

`/* doiuse-enable feature */`

Enables checks of specified feature(s) (can be comma separated list)

for following lines in file

Contributing

doiuse is an OPEN Open Source Project.

This means that individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project.

License

MIT