jQuery.isFunction()

Categories: Deprecated > Deprecated 3.3 | Utilities

jQuery.isFunction( value )Returns: booleanversion deprecated: 3.3, removed: 4.0

Description: Determines if its argument is callable as a function.

As of jQuery 3.3, jQuery.isFunction() has been deprecated. In most cases, its use can be replaced by typeof x === "function".

Note: As of jQuery 1.3, functions provided by the browser like alert() and DOM element methods like getAttribute() are not guaranteed to be detected as functions in browsers such as Internet Explorer.

Examples:

Example 1

Test a few parameter examples.

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<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>jQuery.isFunction demo</title>
  <style>
  div {
    color: blue;
    margin: 2px;
    font-size: 14px;
  }
  span {
    color: red;
  }
  </style>
  <script src="https://code.jquery.com/jquery-3.7.1.js"></script>
</head>
<body>
 
<div>jQuery.isFunction( objs[ 0 ] ) = <span></span></div>
<div>jQuery.isFunction( objs[ 1 ] ) = <span></span></div>
<div>jQuery.isFunction( objs[ 2 ] ) = <span></span></div>
<div>jQuery.isFunction( objs[ 3 ] ) = <span></span></div>
<div>jQuery.isFunction( objs[ 4 ] ) = <span></span></div>
 
<script>
function stub() {}
var objs = [
  function() {},
  { x:15, y:20 },
  null,
  stub,
  "function"
];
 
jQuery.each( objs, function( i ) {
  var isFunc = jQuery.isFunction( objs[ i ]);
  $( "span" ).eq( i ).text( isFunc );
});
</script>
 
</body>
</html>

Demo:

Example 2

Finds out if the parameter is a function.

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$.isFunction(function() {});

Result:

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true