current x,y coordinates of cursor in text area using javascript

How can i get current x & y position of my CURSOR within a text area using javascript. The event is a Keyup event, not a mouse event.

I am not looking for the c开发者_JAVA百科urrent cursor position in terms of charecter but x , y coordinates.

The only somewhat reliable method I can think of is this:

1. Create a <span> offscreen (absolutely positioned way to the left)
2. Give it the same font characteristics as the input element.
3. Continuously populate it with the text from the input element but before the caret
4. Use a javascript library to find the pixel width of the offscreen span
5. Use that to determine where the caret is relative to the left side of the input element.

Give it a shot, I'd love to hear how it turns out.

Give this a shot:

 $(document).ready(function(){
    $('textarea').bind('keyup', function(e){
      var $this = $(this);
      alert('X: ' + $this.data('mousepos').x + '\nY: ' + $this.data('mousepos').y);
    });

    $('textarea').bind('mousemove', function(e){
      $(e.target).data('mousepos', {x: e.pageX, y: e.pageY});
    });
 });​

workin example: http://jsbin.com/ibowa3/edit