为dom元素添加resize事件

为dom元素添加resize事件

 // 添加resize 事件
    function addresize(dom, fn) {
        var w = dom.offsetWidth,
            h = dom.offsetHeight,
            oldfn = window.onresize;
        if (oldfn) {
            window.onresize = function () {
                oldfn.call(window);
                if (dom.offsetWidth != w || dom.offsetHeight != h) {
                    w = dom.offsetWidth;
                    h = dom.offsetHeight;
                    fn.call(dom);
                }
            }
        } else {
            window.onresize = function () {
                if (dom.offsetWidth != w || dom.offsetHeight != h) {
                    w = dom.offsetWidth;
                    h = dom.offsetHeight;
                    fn.call(dom);
                }
            }
        }
    }