jQuery isFunction() exmaple

jQuery isFunction() function is used to determines if its argument is callable as a function.

Syntax

jQuery.isFunction( value )
value - The value to be tested.

Example

Test a few parameter examples.
<!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-3.4.1.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>
Output:
jQuery.isFunction( objs[ 0 ] ) = true
jQuery.isFunction( objs[ 1 ] ) = false
jQuery.isFunction( objs[ 2 ] ) = false
jQuery.isFunction( objs[ 3 ] ) = true
jQuery.isFunction( objs[ 4 ] ) = false

References

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