首先我们应用上次的内容——方块拖拽，利用方块拖拽来让两个方块进行碰撞。
我们可以先定义两个正方形方块，红色的div1,绿色的div2,我们来实现当div1碰撞div2时div2的颜色变为黄色
HTML代码如下：定义方块
1 <!DOCTYPE html>
2 <html lang="en">
3
4 <head>
5 <meta charset="UTF-8">
6 <meta http-equiv="X-UA-Compatible" content="IE=edge">
7 <meta name="viewport" content="width=device-width, initial-scale=1.0">
8 <title>Document</title>
9 <style>
10 body {
11 margin: 0;
12 }
13 #div1 {
14 width: 100px;
15 height: 100px;
16 background: red;
17 position: absolute;
18 left: 0;
19 top: 0;
20 }
21
22 #div2 {
23 width: 100px;
24 height: 100px;
25 background: green;
26 position: absolute;
27 left: 500px;
28 top: 200px;
29 }
30 </style>
31 </head>
32
33 <body>
34 <div id="div1"></div>
35 <div id="div2"></div>
36 </body>
37
38 </html>
利用上个文章的的拖拽内容：令div1可以拖拽
1 <script>
2 var div1 = document.getElementById('div1')
3 var div2 = document.getElementById('div2')
4
5 div1.onmousedown = function (event) {
6 var chaX = event.clientX - div1.offsetLeft
7 var chaY = event.clientY - div1.offsetTop
8
9 document.onmousemove = function (event) {
10 div1.style.left = event.clientX - chaX + 'px'
11 div1.style.top = event.clientY - chaY + 'px'
12 }
13
14 document.onmouseup = function () {
15 document.onmousemove = null
16 }
17
18
19 }
20
21
22 </script>
因为我们每次拖拽都要判断是否碰撞，我们的碰撞代码应该放在移动的里面
添加后：
1 <script>
2 var div1 = document.getElementById('div1')
3 var div2 = document.getElementById('div2')
4
5 div1.onmousedown = function (event) {
6 var chaX = event.clientX - div1.offsetLeft
7 var chaY = event.clientY - div1.offsetTop
8
9 document.onmousemove = function (event) {
10 div1.style.left = event.clientX - chaX + 'px'
11 div1.style.top = event.clientY - chaY + 'px'
12
13 if (div1.offsetLeft + div1.offsetWidth < div2.offsetLeft ||
14 div2.offsetLeft + div2.offsetWidth < div1.offsetLeft ||
15 div1.offsetTop + div1.offsetHeight < div2.offsetTop ||
16 div2.offsetTop + div2.offsetHeight < div1.offsetTop
17 ) {
18 div2.style.backgroundColor = ''
19 } else {
20 div2.style.backgroundColor = 'yellow'
21 }
22
23 }
24 document.onmouseup = function () {
25 document.onmousemove = null
26 }
27 }
28
29 </script>
可以看到我们在移动的代码里添加了判断条件
让div1的左边距加上div1的宽度小于div2的左边距，让div2的左边距加上div2的宽度小于div1的左边距，让div1的上边距加上div1的高度小于div2的上边距，让div2的上边距加上div2的高度小于div1的上边距，满足这些条件就是未碰上。