jQuery change CSS background position and mouseover/mouseout

Question

I have a menu composed of a single image (e.g., sprites). In order to display the hover image, I simply move the background image down. I'd like this effect to be controlled by jQuery and animated.

This is a sample menu item.

 <ul>
  <li id="home"><a href="#"></a></li>
 </ul>

This is what I'm toying with. I'm very new to jQuery and am having problems getting the proper selector going.

 $(document).ready(function(){

  $('#home a');

   // Set the 'normal' state background position
   .css( {backgroundPosition: "0 0"} )

   // On mouse over, move the background
   .mouseover(function(){
    $(this).stop().animate({backgroundPosition:"(0 -54px)"}, {duration:500})
   })

   // On mouse out, move the background back
   .mouseout(function(){
    $(this).stop().animate({backgroundPosition:"(0 0)"}, {duration:500})
   })

 });

Could you point out what I'm doing wrong? I know the selector is probably incorrect but I'm having a hard time figuring out how to manipulate the anchor.

Answer 1

I would imagine your background is bound to the li?! However this is set to the a of the selector, so if my assumption is correct you would need to change your code to

$(document).ready(function(){

  $('#home a')

   // On mouse over, move the background on hover
   .mouseover(function(){
    $(this).parent().stop().animate({backgroundPosition:"(0 -54px)"}, {duration:500})
   })

   // On mouse out, move the background back
   .mouseout(function(){
    $(this).parent().stop().animate({backgroundPosition:"(0 0)"}, {duration:500})
   })

 });

Answer 2

{backgroundPosition:"(0 -54px)"

(You don't want the brackets there. There's no brackets in a CSS background-position rule.)

In any case jQuery doesn't know how to animate a compound value like backgroundPosition. In IE you get access to it with backgroundPositionY, which, as a simple value, jQuery can animate. However this is non-standard and won't work elsewhere.

Here's a plugin that claims to fix it.

Answer 3

         $('#home a')
.mouseenter(function(){
        $(this).parent().stop().animate({backgroundPosition:"(0 -54px)"},500)
       })
.mouseleave(function(){
        $(this).parent().stop().animate({backgroundPosition:"(0 0)"},500)
       })

//Use MouseEnter and MouseLeave whenever possible and you do not need to type out duration with the current version of jQuery. Hope this helps.