Pure javascript to get the style of an element

function getStyle(dom) {
        var style;
        var returns = {};
        /**
         * This statement determines whether computed style is available for the DOM element
         */
        if (window.getComputedStyle) {
            style = window.getComputedStyle(dom, null);
            for (var i = 0; i < style.length; i++) {
                var prop = style[i];
                var val = style.getPropertyValue(prop);
                returns[prop] = val;
            }
            return returns;
        }
        /**
         * This statement determines whether inline style is available for the DOM element
         */
        if (dom.currentStyle) {
            style = dom.currentStyle;
            for (var prop in style) {
                returns[prop] = style[prop];
            }
            return returns;
        }
        /*
         * This statement determines whether the style is specified within some stylesheet for the DOM element
         */
        if (style = dom.style) {
            for (var prop in style) {
                if (typeof style[prop] != 'function') {
                    returns[prop] = style[prop];
                }
            }
            return returns;
        }
        return returns;
    }