Getting DIV id based on x & y position

Question

The problem I\'m trying to solve is \"What\'s at this position?\"

It\'s fairly trivial to get the x/y position (offset) of a DIV, but what about the reverse? How do

Answer 1

One option is to build an array of "div-dimension" objects. (Not to be confused with the divs themselves... IE7 perf is frustrating when you read dimensions off of object.)

These objects consist of a pointer to the div, their dimensions (four points... say top, left, bottom, and right), and possibly a dirty bit. (Dirty bit is only really needed if the sizes change.

You could then iterate through the array and check dimensions. It requires O(n) to do that on each mouse move. You might be able to do slightly better with a binary search style approach... maybe.

If you do a binary search style approach, one way is to store 4 arrays. Each with a single point of the dimension, and then binary search on all four. O(4logn) = O(logn).

I'm not saying I recommend any of these, but they MIGHT work.