Skip to content

Pass function as parameter JavaScript | Example code

  • by

JavaScript Functions are ‘first class’ and treated like any other variable. When the function is passed as a parameter to another function, they’re known as a ‘callback’ in JavaScript. That is called when the other function is ready for them.

Example Pass function as parameter JavaScript

Simple example code. If you want to pass a function, just reference it by name without the parentheses:


    <script type="text/javascript">

      function foo(x) {

      function bar(func) {
        func("Hello World!");

      //alerts "Hello World!"



Pass function as parameter JavaScript

But sometimes you might want to pass a function with arguments included, but not have it called until the callback is invoked. To do this, when calling it, just wrap it in an anonymous function, like this:

function foo(x) {
function bar(func) {

//alerts "Hello World!" (from within bar AFTER being passed)
bar(function(){ foo("Hello World!") });

If you prefer, you could also use the apply function and have a third parameter that is an array of the arguments, like such:

function eat(food1, food2)
    alert("I like to eat " + food1 + " and " + food2 );
function myFunc(callback, args)
    //do stuff
    //execute callback when finished
    callback.apply(this, args);

//alerts "I like to eat pickles and peanut butter"
myFunc(eat, ["pickles", "peanut butter"]); 


Do comment if you have any doubts or suggestions on this JS function topic.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.

OS: Windows 10

Code: HTML 5 Version

Leave a Reply

Your email address will not be published. Required fields are marked *