Can one use javascript to find if one <div> element is covering/over another

[turgon]

At the moment I making an ajax based file manager system. Im approched by a tricky problem. As in windows explorer etc I want users to be able to select any free space, click down, and drag a semi-transparent box around that will automaticly select any file/folder elements it covers over.

In a more general sense, take this tutorial page with the three movable objects. I can lift Item 1 and place it over Item 2. But can I use javascript now, so that it automaticly triggers a function because Item 2 is covering Item 1.

So basiccaly Im wondering is there any way to determine if one <div> is covering another?? Cheers for any ideas!

[acoder]

If all you want is the divs covered by the semi-transparent box, why not check the positions of the divs on mouse up?

[turgon]

Well I want the elements to change color as they are highlighted. And doing a co-ordinates comparision of every element with the selecting box every time the mouse moves would be too memory intensive.

[acoder]

Is the instant highlighting a must? If not, you can use transparency and a dimming effect to make it obvious which are selected. What about onmouseover for the divs and you can use bubbling/capturing (see article) for multiple divs on top of each other.