animate fails with 0 duration

[jarkaruus]

Switching from 1.7.2 to 1.8 some plugins using animate with a duration of 0 don't animate at all in certain situations.

$(element).animate({ left: '-400px' }, 0, function() {}); // broken since 1.8
$(element).animate({ left: '-400px' }, 1, function() {}); // works

My guess is that a type check was changed into something else.

[addyosmani]

Thanks for submitting a ticket to the jQuery bug tracker. Could you reply back with a test case on jsFiddle.net reproducing the issue? If you could also test against jQuery-Git to ensure this hasn't been fixed by the latest version that would be appreciated.

[jarkaruus]

Here is the fiddle: ​http://jsfiddle.net/LQMzb/

The problem is there when having both jQuery UI 1.8.22 and jQuery 1.8 on the page.

[scottgonzalez]

Hmm...this works against jQuery UI master, so it's probably a bug in UI. I'll dig into this today and find out which bug tracker this belongs in.

[scottgonzalez]

What's happening is jQuery 1.8 now performs a single tick animation, while 1.7.2 skipped the animation. Was that an intentional change? This breaks in old jQuery UI because the easing equations that everybody uses (including jQuery UI) rely on duration. jQuery UI master works because we rewrote all easing equations to only rely on state. So this is a breaking change. We can fix it in jQuery UI 1.8.23, but anyone using the easing plugin on its own will have broken animations for a duration of 0.

[scottgonzalez]

This is now fixed in jQuery UI 1-8-stable and will be included in 1.8.23 this week. See ​http://bugs.jqueryui.com/ticket/8493.

[jarkaruus <ts.jarkaruus@…>]

Awesome, thanks

[jarkaruus]

Now that the extra easing equations have been reduced to a few lines of code maybe it makes sense to move them into jQuery so all of them are in one place?

[scottgonzalez]

@sindresorhus I didn't see any commits for this, how did it get fixed?

[gnarf]

The issue here is passing a 0 duration to an easing function, if the duration is 0 it probably should skip easing altogether.

[gnarf]

​https://github.com/jquery/jquery/pull/895

[Corey Frang]

Fix #12273. Don't call easing functions for duration 0 animations. Close gh-895.

Changeset: 0fea007a1a4d6456a8c7d246e4f7a4e14a1ba04a