Adonis K.

Frontend Engineer

How to add callback to a function

We all know and love JQuery's callback and since I love it so much I wanted to replicate when I started recreating codemagic. It seems like it's rather easy to do, all you have to do is add another parameter named callback (you can name it whatever you want, I just prefer it this way) and after checking wether the parameter is a function, execute it before the end of the container function. Here is an example:

// create a function that can take 2 parameters,
// a target variable
// and an optional callback function
increase = function (target, callback) {
    // incrase target's height by 10% = * 1.1 || '150px';

    // and if the the callback parameter exists and is a type of function
    if (callback && typeof callback == 'function') {
        // call it

// usage example
var body = document.querySelector('body');
increase(body, function() {