JavaScript计时器

JavaScript计时器

doctype html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport"
    content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>JavaScript计时器title>

  <style>
    body {
      padding: 40px;
      margin: 0;
    }

    .timeTitle {
      font-size: 28px;
      line-height: 80px;
    }

    #timeNow {
      color: #67c23a;
    }

    .btn {
      display: inline-flex;
      justify-content: center;
      align-items: center;
      line-height: 1;
      height: 32px;
      white-space: nowrap;
      cursor: pointer;
      color: #FFFFFF;
      text-align: center;
      box-sizing: border-box;
      outline: none;
      transition: .1s;
      font-weight: 500;
      user-select: none;
      vertical-align: middle;
      -webkit-appearance: none;
      background-color: #409eff;
      border: 1px solid #dcdfe6;
      border-color: #409eff;
      padding: 8px 15px;
      font-size: 14px;
      border-radius: 4px;
      margin-right: 16px;
    }

    .btn:last-child {
      margin-right: 0;
    }

    .btn:hover {
      background-color: #79bbff;
      border-color: #79bbff;
    }

    .warning {
      background-color: #e6a23c;
      border-color: #e6a23c;
    }

    .warning:hover {
      background-color: #eebe77;
      border-color: #eebe77;
    }

    .danger {
      background-color: #f56c6c;
      border-color: #f56c6c;
    }

    .danger:hover {
      background-color: #f89898;
      border-color: #f89898;
    }
  style>
head>

<body>

  <div class="timeTitle">当前时间为:<span id="timeNow">00:00:00span>div>
  <button class="btn" id="timeBegin">计时开始button>
  <button class="btn warning " id="timeEnd">计时结束button>
  <button class="btn danger" id="timeClear">计时清除button>

  <script>
    // 定义初始值 计时器
    var timer = "";
    // 开始计时
    var beginBtn = document.getElementById("timeBegin");
    var endBtn = document.getElementById("timeEnd");
    var clearBtn = document.getElementById("timeClear");

    var beginNum = 0;

    // 定义:分  秒  毫秒
    var min, second, millisecond;
    // 初始化数据
    min = second = millisecond = 0;

    // 定时器
    function time() {
      millisecond += 50;
      if (millisecond >= 1000) {
        millisecond = 0
        second += 1;
      }
      if (second >= 60) {
        second = 0
        min += 1;
      }
      counts = min + ':' + second + ':' + millisecond;
      document.getElementById("timeNow").innerText = counts;
    }

    //开始计时
    function BeginTime() {
      beginBtn.onclick = function () {
        if (beginNum > 0) {
          return;
        }
        beginNum++;
        timer = setInterval(time, 50);
      }
    }
    //结束计时
    function EndTime() {
      endBtn.onclick = function () {
        beginNum = 0;
        clearInterval(timer);
      }
    }
    //计时清除
    function ClearTime() {
      clearBtn.onclick = function () {
        beginNum = 0;
        clearInterval(timer);
        document.getElementById("timeNow").innerHTML = "00:00:00";
      }
    }

    BeginTime();
    EndTime();
    ClearTime()
  script>
body>

html>

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