event.dataReturns: Object

Description: An optional object of data passed to an event method when the current executing handler is bound.

version added: 1.1event.data

Example:

Within a for loop, pass the value of i to the .on() method so that the current iteration's value is preserved.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>event.data demo</title>
  <script src="https://code.jquery.com/jquery-4.0.0.js"></script>
</head>
<body>
<button> 0 </button>
<button> 1 </button>
<button> 2 </button>
<button> 3 </button>
<button> 4 </button>
<div id="log"></div>
<script>
var logDiv = $( "#log" );
for ( var i = 0; i < 5; i++ ) {
  $( "button" ).eq( i ).on( "click", { value: i }, function( event ) {
    var msgs = [
      "button = " + $( this ).index(),
      "event.data.value = " + event.data.value,
      "i = " + i
    ];
    logDiv.append( msgs.join( ", " ) + "<br>" );
  });
}
</script>
</body>
</html>

event.dataReturns: Object

version added: 1.1event.data

Demo: