var Drag = {            // 拖拽元素            obj: null,            //el: 拖拽元素            //minX: X轴最小边界            //minY: Y轴最小边界            //maxX: X轴最大边界            //maxY: X轴最大边界            init: function(el,minX,maxX,minY,maxY){                this.obj = el;                if(isNaN(this.getLocation().x))                    this.obj.style.left = ‘0px‘;                if(isNaN(this.getLocation().y))                    this.obj.style.top = ‘0px‘;                this.obj.onmousedown = function(e){                    Drag.start.call(el,e);                };                this.obj.minX = minX;                this.obj.minY = minY;                this.obj.maxX = maxX;                this.obj.maxY = maxY;            },            start: function(e){                e = Drag.fixEvent(e);                this.inDOMLocation = {                    x: e.layerX,                    y: e.layerY                };                this.oldLocation = {                    x: e.clientX,                    y: e.clientY                };                //设定鼠标的移动范围                if(this.minX)                    this.minMouseX = e.layerX + this.minX;                if(this.minY)                    this.minMouseY = e.layerY + this.minY;                if(this.maxX)                    this.maxMouseX = this.maxX - (this.offsetWidth - (parseInt(this.clientLeft) || 0) - e.layerX)                if(this.maxY)                    this.maxMouseY = this.maxY - (this.offsetHeight - (parseInt(this.clientTop) || 0) - e.layerY)                this.onmousemove = function(e){                    Drag.drag.call(Drag.obj,e);                };                this.onmouseup = function(e){                    Drag.stop.call(Drag.obj,e);                };            },            drag: function(e){                e = Drag.fixEvent(e);                var newLocation = {                    x: e.clientX,                    y: e.clientY                }, x,y;                x = newLocation.x;                y = newLocation.y;                if(this.minMouseX)                    x = Math.max(this.minMouseX,newLocation.x)                if(this.minMouseY)                    y = Math.max(this.minMouseY,newLocation.y)                if(this.maxMouseX)                    x = Math.min(this.maxMouseX,x)                if(this.maxMouseY)                    y = Math.min(this.maxMouseY,y)                this.style.left = Drag.getLocation().x + (x - this.oldLocation.x) + ‘px‘;                this.style.top = Drag.getLocation().y + (y - this.oldLocation.y) + ‘px‘;                this.oldLocation = {                    x: x,                    y: y                }                return;            },            stop: function(){                this.oldLocation = null;                this.inDOMLocation = null;                this.onmouseup = this.onmousemove = null            },            fixEvent: function(e){                e = e || window.event;                if(!e.layerX)                    e.layerX = e.offsetX;                if(!e.layerY)                    e.layerY = e.offsetY;                if(!e.pageX)                    e.pageX = e.clientX + document.body.scrollLeft - document.body.clientLeft;                if(!e.pageY)                    e.pageY = e.clientY + document.body.scrollTop - document.body.clientTop;                return e;            },            getLocation: function(){                var location = {},style;                if(window.getComputedStyle){                    style = window.getComputedStyle(this.obj,‘‘);                    location.x = parseInt(style.getPropertyValue(‘left‘));                    location.y = parseInt(style.getPropertyValue(‘top‘));                }else{                    style = this.obj.currentStyle;                    location.x = parseInt(style[‘left‘]);                    location.y = parseInt(style[‘top‘]);                }                return location;            }        }