javascript get style pixel value in ie6 and ie7

var PIXEL = /^\d+(px)?$/i;
function getPixelValue(element, value) {
if (PIXEL.test(value)) return parseInt(value);
var style = element.style.left;
var runtimeStyle = element.runtimeStyle.left;
element.runtimeStyle.left = element.currentStyle.left;
element.style.left = value || 0;
value = element.style.pixelLeft;
element.style.left = style;
element.runtimeStyle.left = runtimeStyle;
return value;
};

Reference: http://erik.eae.net/archives/2007/07/27/18.54.15/#comment-102291