Jquery animate bottom problem

It's strange. I have an animation that start when i .hover on a DIV. Into this div i have another in position absolute that i want to move up until the mouse stay on main div and go down in your position when i go out of main div. A simple hover effect. I have write down this function that work well apart a strange bug.

         var inside = $('.inside')

         ins开发者_Python百科ide.hover(function() {
             $(this).children(".coll_base").stop().animate({
               bottom:'+=30px'
             },"slow")
          }, function() {
             $(this).children(".coll_base").stop().animate({
               bottom:'-=30px'
             },"slow");
          });

i need +=30 and -=30 because i have to apply this function to a range of div with different bottom. The problem is that if i hover on and out of div the DIV animate right but when go down he decrease the value of bottom every animation. If i go up and down from the main div i see that the animated div go down even beyond the main div. I think that i miss something to resolve this bug. Thanks for any help

If the bottom is not 0 initially, then you could store the initial bottom value, and use that in the second function. (If the initial bottom is 0, then just use that.)

In the example below, the initial bottom position is stored using the data() attribute for inside, then it is retrieved in the second handler to return to the original position.

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

var inside = $('.inside');

inside.hover(
    function() {
        if(!inside.data('bottom')) {
            inside.data('bottom',$(this).children(".coll_base").css('bottom'));
        }
        $(this).children(".coll_base").stop().animate({ bottom:'+=30px' },"slow")
    }, 
    function() {
        $(this).children(".coll_base").stop().animate({bottom:$(this).data('bottom') },"slow");
    }
);​

I don't think you can use relative (-=30px and +=30px) values in this case, as the animation can stop at any arbitrary point which will throw out the animations that follow it. Best to call each() on the matched set, calculate the correct offsets and pass the values directly into your hover function.