jquery implements countdown effect_jquery-JS Tutorial-php.cn

jquery implements countdown effect_jquery

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Release： 2016-05-16 15:25:45

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Design a small game of answering questions. Each question can be answered in 20 seconds. If the time is exceeded, a corresponding reminder will be given. Since 20 seconds is too long, it is not suitable for making GIF animations. Let’s take a look at what I wrote. The results of the 5-second countdown test program:

1. Main program

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <title>手写倒计时程序</title>
    <link rel="stylesheet" type="text/css" href="css/layout.css"/>
  </head>
  <body>
    <section class="countDown">
      <span id="countDownTime"></span>
      <section class="clear"></section>
    </section>
    <script src="js/jquery-1.11.0.js" type="text/javascript" charset="utf-8"></script>
    <script src="js/layout.js" type="text/javascript" charset="utf-8"></script>
  </body>
</html>

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2. CSS style

*{
  margin: 0;
  padding:0;
}
html{
  font-size: 12px;
}
.countDown{
  width: 3.8rem;
  text-align: center;
  margin: 2rem auto 0 auto;
}
.countDown #countDownTime{
  font-size: 2rem;
}

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3. Jquery program

First let’s talk about the principle of countdown:

1. Convert the time to 0:0 format

2. You need to start a timer to automatically reduce the time by 1 every 1000ms

3. Determine whether the time is 0. If it is 0, it means the timer is over. At this time, you need to give a prompt or do other things

Let’s look at the specific implementation of the countdown program:

$(function(){
  var countDownTime=parseInt(5);    //在这里设置每道题的答题时长
  function countDown(countDownTime){
    var timer=setInterval(function(){
      if(countDownTime>=0){
        showTime(countDownTime);
        countDownTime--;
      }else{
        clearInterval(timer);
        alert("计时结束,给出提示");
      }
    },1000);
  }
  countDown(countDownTime);
  function showTime(countDownTime){      //这段是计算分和秒的具体数
    var minute=Math.floor(countDownTime/60);
    var second=countDownTime-minute*60;
    $("#countDownTime").text(minute+":"+second);
  }
})

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It will probably be easier to look at this JS program with the principles I wrote. I hope it will be helpful to my friends.