jQuery isFunction() method
The jQuery.isFunction() method is a utility function in jQuery used to check whether a given value is a function or not. It is designed to provide a consistent way of determining if a variable is a function, even in older browsers where the native typeof operator may not be sufficient for accurate function detection.
Here’s the basic syntax of the jQuery.isFunction() method:
jQuery.isFunction(obj)Parameters:
obj: The variable or value to be tested.
Return Value:
The jQuery.isFunction() method returns true if the specified value is a function, and false otherwise.
Example:
<!DOCTYPE html>
<html>
<head>
<title>jQuery isFunction() Method Example</title>
<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
</head>
<body>
<script>
$(document).ready(function() {
var myFunction = function() {
alert("Hello, I am a function!");
};
var myString = "Hello, world!";
// Check if the variables are functions
var isMyFunction = jQuery.isFunction(myFunction);
var isMyStringFunction = jQuery.isFunction(myString);
// Log the results to the console
console.log("myFunction is a function:", isMyFunction); // true
console.log("myString is a function:", isMyStringFunction); // false
});
</script>
</body>
</html>In this example, we have two variables: myFunction and myString. We use the jQuery.isFunction() method to check whether each of these variables is a function or not. The method returns true for the myFunction variable because it is a function, and false for the myString variable because it is not a function.
Keep in mind that starting from jQuery version 3.0, the recommended way to check if a variable is a function is to use the native typeof operator:
typeof obj === 'function'Using typeof for function detection is more widely supported in modern browsers and is the standard way to check for function types in JavaScript.
For modern projects, it is generally preferable to use the typeof approach for better compatibility and performance. However, the jQuery.isFunction() method remains available in jQuery for backward compatibility with older codebases or specific use cases.