getElementOffset.js

getElementOffset.js

function getElementOffset(el)
{
	for (var offsetTop = 0, offsetLeft = 0; el.offsetParent; el = el.parentNode)
	{
		offsetTop += el.offsetTop;
		offsetLeft += el.offsetLeft;
	}

	return {
		offsetTop: offsetTop,
		offsetLeft: offsetLeft
	};
}

// gf3 style

function getElementOffset(el) {
	var offsetTop = 0, offsetLeft = 0;

	if (el.offsetParent)
	{
		do {
			offsetTop  += el.offsetTop;
			offsetLeft += el.offsetLeft;
		} while (el = el.offsetParent);
	}

	return {
		offsetTop: offsetTop,
		offsetLeft: offsetLeft
	};
}

Here's my version:

function offset ( el ) {
  var left = 0, top = 0
  if ( el.offsetParent )
    do {
      left += el.offsetLeft
      top  += el.offsetTop
    } while ( el = el.offsetParent )
  return { 0: left, 1: top, left: left, top: top, length: 2 }
}

Great ideas, @gf3, and I think it could be smaller too.