April 29, 2012

How do I animate in jQuery without stacking callbacks?

Question by yuval

Let’s say I have three divs, and I’d like each to animate once the previous one is done. Currently, I write this:

$('div1').fadeOut('slow', function() {
    $('div2').fadeOut('slow', function() {

Which is ugly, but manageable.

Now imagine I have 10 different animations that need to happen one after the other on different elements. Suddenly the code gets so clunky that it’s extremely hard to manage…

Here’s pseudocode for what I’m looking to do:

$('div1').fadeOut('slow' { delay_next_function_until_done: true } );
$('div2').fadeOut('slow' { delay_next_function_until_done: true } );
$('div3').animate({ top: 500 }, 1000 );

How do I achieve this?

Answer by Julian Aubourg

If you’re using a recent version of jQuery, use the animation promises:

$('div1').fadeOut('slow' ) ).promise().pipe(function() {
    return $('div2').fadeOut('slow' );
}).pipe(function() {
    return $('div3').animate({ top: 500 }, 1000 );

You can make it generic:

$.chain = function() {
    var promise = $.Deferred().resolve().promise();
    jQuery.each( arguments, function() {
        promise = promise.pipe( this );
    return promise;

var animations = $.chain(function() {
    return $('div1').fadeOut('slow');
}, function() {
    return $('div2').fadeOut('slow');
}, function() {
    return $('div3').animate({ top: 500 }, 1000 );

$.when( animations ).done(function() {

Still a lot of function closures but that’s the very nature of Javascript. However, it’s much more natural and a lot more flexible using Deferreds/Promises since you avoid callbacks “inception”.

Answer by Starx

Callback is a friend, dont push it away. There are ways to simplify them. Here is one of them

$('div1').fadeOut('slow', div2)
function div3() { $('div3').fadeOut('slow'); }
function div2() { $('div2').fadeOut('slow', div3); }

Author: Nabin Nepal (Starx)

Hello, I am Nabin Nepal and you can call me Starx. This is my blog where write about my life and my involvements. I am a Software Developer, A Cyclist and a Realist. I hope you will find my blog interesting. Follow me on Google+


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