using jQuery .animate to animate a div from right to left?

Question

I have a div absolutely positioned at top: 0px and right: 0px, and I would like to use jquery's .animate() to animate it from it's current position to left: 0px. How does one do this? I can't seem to get this to work:

$("#coolDiv").animate({"left":"0px"}, "slow");

Why doesn't this work and how does one accomplish what I am looking to do?

Thanks!!

Answer 1

I think the reason it doesn't work has something to do with the fact that you have the right position set, but not the left.

If you manually set the left to the current position, it seems to go:

Live example: http://jsfiddle.net/XqqtN/

var left = $('#coolDiv').offset().left;  // Get the calculated left position

$("#coolDiv").css({left:left})  // Set the left to its calculated position
             .animate({"left":"0px"}, "slow");

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EDIT:

Appears as though Firefox behaves as expected because its calculated left position is available as the correct value in pixels, whereas Webkit based browsers, and apparently IE, return a value of auto for the left position.

Because auto is not a starting position for an animation, the animation effectively runs from 0 to 0. Not very interesting to watch. :o)

Setting the left position manually before the animate as above fixes the issue.

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If you don't like cluttering the landscape with variables, here's a nice version of the same thing that obviates the need for a variable:

$("#coolDiv").css('left', function(){ return $(this).offset().left; })
             .animate({"left":"0px"}, "slow");    ?