js实现可拖动DIV的方法(2)

var $ = function (flag) {
                return document.getElementById(flag);
            }    

2.捕捉document的mousedown事件：

里面有这么一段代码：

复制代码 代码如下:

     var page = {
                    event: function (evt) {
                        var ev = evt || window.event;
                        return ev;
                    },
                    pageX: function (evt) {
                        var e = this.event(evt);
                        return e.pageX || (e.clientX + document.body.scrollLeft - document.body.clientLeft);
                    },
                    pageY: function (evt) {
                        var e = this.event(evt);
                        return e.pageY || (e.clientY + document.body.scrollTop - document.body.clientTop);