getElementStyle.js

function elementGetStyle(element, style) {
    var value = element.style[style];
    if (!value) {
        if (document.defaultView && document.defaultView.getComputedStyle) {
            var css = document.defaultView.getComputedStyle(element, null);
            value = css ? css.getPropertyValue(style) : null;
        } else if (element.currentStyle) {
            value = element.currentStyle[style];
        }
    }

    return value == 'auto' ? null : value;
}