jQuery isFunction() method

The isFunction() method is used to test whether the passed argument is a function or not. This method returns a Boolean value. If it finds the passed value is a function, it returns true. Otherwise, it returns false.

Syntax

This method accepts a single parameter, which is defined as follows -

val - It is any value to be tested.

Let's understand the working of the isFunction() method using an illustration.

Example

In this example, we are using the isFunction() method to determine whether the passed values are function or not. Here, we are passing different values such as null, undefined, etc., as an argument.

<!DOCTYPE html> 
<html> 

<head> 
	<title> jQuery isFunction() method </title> 
	<script src = "https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"> </script> 
</head> 
<body> 
	<h1> Welcome to the javaTpoint.com </h1> 
	<h3> It is an example of using the isFunction() method. </h3> 
	<p> Is "function() {}" is a function? <b id = "b1"> </b> </p> 
	<p> Is "{ x : 28, y : 32}" is a function? <b id = "b2"> </b> </p> 
	<p> Is "null" is a function? <b id = "b3"> </b> </p> 
	<p> Is "undefined" is a function? <b id = "b4"> </b> </p> 	
	<script> 
		var a = jQuery.isFunction(function() {}); 
		var b = jQuery.isFunction({ x : 28, y : 32 }); 
		var c = jQuery.isFunction(null); 
		var d = jQuery.isFunction(undefined); 
		$( "#b1" ).text( a ); 
		$( "#b2" ).text( b ); 
		$( "#b3" ).text( c ); 
		$( "#b4" ).text( d ); 
	</script> 
</body> 
</html>

Test it Now

Output

After the execution of the above code, the output will be -