|
@@ -0,0 +1,69 @@
|
|
|
|
|
+<!DOCTYPE html>
|
|
|
|
|
+<html lang="en">
|
|
|
|
|
+<head>
|
|
|
|
|
+ <meta charset="UTF-8">
|
|
|
|
|
+ <meta name="viewport" content="width=device-width, initial-scale=1.0">
|
|
|
|
|
+ <title>Document</title>
|
|
|
|
|
+ <style>
|
|
|
|
|
+ .box{
|
|
|
|
|
+ width: 300px;
|
|
|
|
|
+ height: 300px;
|
|
|
|
|
+ background-color: #aaa;
|
|
|
|
|
+ position: fixed;
|
|
|
|
|
+ top: 50%;
|
|
|
|
|
+ left: 50%;
|
|
|
|
|
+ margin-top: -150px;
|
|
|
|
|
+ margin-left: -150px;
|
|
|
|
|
+ text-align:center;
|
|
|
|
|
+ }
|
|
|
|
|
+ p{
|
|
|
|
|
+ font-size: 50px;
|
|
|
|
|
+ color: #fff;
|
|
|
|
|
+ font-weight: bold;
|
|
|
|
|
+ text-align: center;
|
|
|
|
|
+ }
|
|
|
|
|
+ button{
|
|
|
|
|
+ width: 100px;
|
|
|
|
|
+ height: 50px;
|
|
|
|
|
+ background-color:#fff;
|
|
|
|
|
+ font-size:30px;
|
|
|
|
|
+ }
|
|
|
|
|
+ </style>
|
|
|
|
|
+</head>
|
|
|
|
|
+<body>
|
|
|
|
|
+ <div class="box">
|
|
|
|
|
+ <p>100</p>
|
|
|
|
|
+ <button>开始</button>
|
|
|
|
|
+ </div>
|
|
|
|
|
+ <script>
|
|
|
|
|
+ // 第一步：获取要控制的元素
|
|
|
|
|
+ var num = document.getElementsByTagName("p")[0];
|
|
|
|
|
+ var btn = document.getElementsByTagName("button")[0];
|
|
|
|
|
+ var timer = 0;
|
|
|
|
|
+ // 第二步：给按钮绑定事件
|
|
|
|
|
+ btn.onclick = function(){
|
|
|
|
|
+ if(btn.innerText == "开始"){
|
|
|
|
|
+ btn.innerText = "暂停";
|
|
|
|
|
+ // 开始倒计时-1
|
|
|
|
|
+ timer = setInterval(function(){
|
|
|
|
|
+ num.innerText--;
|
|
|
|
|
+ },1000)
|
|
|
|
|
+ console.log(timer);
|
|
|
|
|
+ }else{
|
|
|
|
|
+ btn.innerText = "开始"
|
|
|
|
|
+ // 停止定时器
|
|
|
|
|
+ console.log(timer)
|
|
|
|
|
+ clearInterval(timer)
|
|
|
|
|
+ }
|
|
|
|
|
+ }
|
|
|
|
|
+
|
|
|
|
|
+
|
|
|
|
|
+ // 如果使用on绑定事件绑定多次那么后边绑定的会覆盖前面绑定的事件
|
|
|
|
|
+ // var a = 1;
|
|
|
|
|
+ // var a = 2;
|
|
|
|
|
+ // btn.onclick = function(){
|
|
|
|
|
+ // console.log("hello")
|
|
|
|
|
+ // }
|
|
|
|
|
+ </script>
|
|
|
|
|
+</body>
|
|
|
|
|
+</html>
|
