1 <script src="../cookie.js"></script>
2 <script>
3
4 class Drag{
5 constructor(){
6 this.box = document.querySelector(".box");
7
8 this.init()
9 this.getPos()
10 }
11 init(){
12 var that = this;
13
14 // 因为使用事件监听绑定事件，删除事件时要找原函数，所以提前使用bind计算出改变this之后的新函数
15 this.m = that.move.bind(that);
16 this.u = that.up.bind(that);
17
18 this.box.addEventListener("mousedown",function(eve){
19 var e = eve || window.event;
20 that.x = e.offsetX;
21 that.y = e.offsetY;
22 // console.log(this) //指向box
23 // 使用bind改变this指向之后的新函数，作为事件处理函数
24 document.addEventListener("mousemove",that.m)
25 document.addEventListener("mouseup",that.u)
26 // console.log(this)
27 // 可以看到位置坐标
28 })
29 }
30 move(eve){
31 var e = eve || window.event;
32 // console.log(this)
33 this.box.style.left = e.pageX - this.x + "px";
34 this.box.style.top = e.pageY - this.y + "px";
35 }
36 up(){
37 // 因为bind生成的函数被提前保存了，所以删除的时候找到的还是同一个函数
38 document.removeEventListener("mousemove",this.m)
39 document.removeEventListener("mouseup",this.u)
40 this.setCookie();
41 }
42 setCookie(){
43 var pos = {
44 x:this.box.offsetLeft,
45 y:this.box.offsetTop
46 }
47 setCookie("pos",JSON.stringify(pos),{
48 expires:3
49 })
50 }
51 getPos(){
52 this.pos = JSON.parse(getCookie("pos"))
53 // console.log(this.pos)
54 this.box.style.left = this.pos.x + "px";
55 this.box.style.top = this.pos.y + "px";
56 }
57 }
58
59
60 new Drag()
61 </script>
1 <style>
2 .box{width:100px;height:100px;background: red;position: absolute;left: 0;top:0;}
3 </style>
4
5 <body>
6 <div class="box"></div>
7 </body>
