How to implement a simple stopwatch effect in js-JS Tutorial-php.cn

How to implement a simple stopwatch effect in js

王林

Release： 2020-03-30 11:29:33

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How to implement a simple stopwatch effect in js

Description:

Implement a simple stopwatch, start timing when you click the start button, then the start button changes to pause,

Click pause to pause the timing , click Reset to return to the initial state.

Effect:

How to implement a simple stopwatch effect in js

(Recommended tutorial: javascript tutorial)

The code is as follows:

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>Title</title>
 <style>
 #showTime
 {
  width: 300px;
  height: 60px;
  font-size: 60px;
  line-height: 60px;
 }
 </style>
</head>
<body>
 <div>
 <div id="showTime">00:00:00</div>
 <button id="startBn">启动</button>
 <button id="restBn">复位</button>
 </div>
<script>
 //——————
 var time,showTime,startBn,restBn,pauseDate;
 //布尔开关
 var bool=false;
 //暂停的累计时间
 var pauseTime=0;
  
 init();
 function init() {
 showTime=document.getElementById("showTime");
 startBn=document.getElementById("startBn");
 restBn=document.getElementById("restBn");
 startBn.addEventListener("click",clickHandler);//开始按钮 ~ 暂停按钮
 restBn.addEventListener("click",clickHandler);//复位按钮
 setInterval(animation,16);
 }
  
 //转化时间函数
 function animation() {
 if(!bool) return;
 //前时间减去上次开启时间减去暂停累计时间
 var times=new Date().getTime()-time-pauseTime;
 var minutes=Math.floor(times/60000);//毫秒转化为分钟
 var seconds=Math.floor((times-minutes*60000)/1000);//已知分钟 
 将time减去分钟 除去1000得出 秒
 var ms=Math.floor((times-minutes*60000-seconds*1000)/10);//
 showTime.innerHTML=
  (minutes<10 ? "0" +minutes : minutes)+":"
  +(seconds<10 ? "0"+seconds :seconds)+":"
 +(ms<10 ? "0"+ms : ms);
 }
  
 //点击时的事件
 function clickHandler(e) {
 e= e || window.event;
 if(this===startBn){
  bool=!bool;
  if(bool){
  this.innerHTML="暂停";
  //如果我们上一次暂停时间是空，表示没有暂停过，因此，直接返回0
  //如果上次的暂停时间是有值得，用当前毫秒数减去上次的毫秒数，这样就会得到暂停时间
  pauseTime+=(!pauseDate ? 0 : new Date().getTime()-pauseDate);
  if(time) return;
  time=new Date().getTime();
  return;//是为bool判断跳出
  }
  
  this.innerHTML="启动";
  pauseDate=new Date().getTime();
  return;//是为this是否等于startBn判断跳出
 }
 startBn.innerHTML="启动";
 pauseTime=0;
 pauseDate=null;
 bool=false;
 time=0;
 showTime.innerHTML="00:00:00";
 }
  
</script>
</body>
</html>

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