Getting all css properties of a dom element in pure javascript

get_css_properties.js

    //  Got from this url: http://acuriousanimal.com/blog/2012/07/09/look-mom-no-jquery-getting-all-css-properties-of-a-dom-element-in-pure-javascript/
    function getComputedStyle( dom ) {
        var style;
        var returns = {};
        // FireFox and Chrome way
        if(window.getComputedStyle){
            style = window.getComputedStyle(dom, null);
            for(var i = 0, l = style.length; i < l; i++){
                var prop = style[i];
                var val = style.getPropertyValue(prop);
                returns[prop] = val;
            }
            return returns;
        }
        // IE and Opera way
        if(dom.currentStyle){
            style = dom.currentStyle;
            for(var prop in style){
                returns[prop] = style[prop];
            }
            return returns;
        }
        // Style from style attribute
        if(style = dom.style){
            for(var prop in style){
                if(typeof style[prop] != 'function'){
                    returns[prop] = style[prop];
                }
            }
            return returns;
        }
        return returns;
    };