WeChat applet countdown component implementation code

This article mainly introduces the relevant information about the implementation code of the countdown component of the WeChat applet. Friends in need can refer to the following

Functions: Suitable for limited-time group purchases, product flash sales, etc. in e-commerce applications

Let’s take a look at the final effect first:

##git source: http://git.oschina.net/dotton/CountDown

points Steps - For impatient friends, you can look directly at the last piece of code.

Put text in the wxml file

second: {{second}} micro second:{{micro_second}}

Call

function countdown(that) {
 var second = that.data.second
 if (second == 0) {
  // console.log("Time Out...");
  that.setData({
   second: "Time Out..."
  });
  return ;
 }
 var time = setTimeout(function(){
  that.setData({
   second: second - 1
  });
  countdown(that);
 }
 ,1000)
}

Page({
  data: {
    second: 3
  },
  onLoad: function() {
    countdown(this);
  }
});

in the js file to run the verification, go from 10 to 1s, and then display the time.

So we continue to improve the milliseconds. Note that the step size of milliseconds is limited by the time frequency of the system, so we are accurate to 0.01s, which is 10ms

js

/* 秒级倒计时 */
function countdown(that) {
 var second = that.data.second
 if (second == 0) {
  that.setData({
   second: "Time out!",
   micro_second: "micro_second too."
  });
  clearTimeout(micro_timer);
  return ;
 }
 var timer = setTimeout(function(){
  that.setData({
   second: second - 1
  });
  countdown(that);
 }
 ,1000)
}

/* 毫秒级倒计时 */
// 初始毫秒数，同时用作归零
var micro_second_init = 100;
// 当前毫秒数
var micro_second_current = micro_second_init;
// 毫秒计时器
var micro_timer;

function countdown4micro(that) {
 if (micro_second_current <= 0) {
  micro_second_current = micro_second_init;
 }
 micro_timer = setTimeout(function(){
  that.setData({
   micro_second: micro_second_current - 1
  });
  micro_second_current--;
  countdown4micro(that);
 }
 ,10)
}

Page({
  data: {
    second: 2,
    micro_second: micro_second_init
  },
  onLoad: function() {
    countdown(this);
    countdown4micro(this);
  }
});

wxml file

<text style="display: block;">second: {{second}}s</text>

<text>{{micro_second}}</text>

In this way, when the second-level operation is completed, the millisecond-level timer is clearTimeout, and the text is displayed Add another countdown4micro method for 'micro_second too'

, so that the remaining 0:3:19 89 is displayed in the form of a countdown

function dateformat(second) {
  var dateStr = "";
  var hr = Math.floor(second / 3600);
  var min = Math.floor((second - hr * 3600) / 60);
  var sec = (second - hr * 3600 - min * 60);// equal to => var sec = second % 60;
  dateStr = hr + ":" + min + ":" + sec;
  return dateStr;
}
目前有2个时钟，影响性能，合并下去掉countdown，于是countdown4micro变成以下的样子：

function countdown4micro(that) {

  var loop_second = Math.floor(loop_index / 100);
  // 得知经历了1s
  if (cost_micro_second != loop_second) {
    // 赋予新值
    cost_micro_second = loop_second;
    // 总秒数减1
    total_second--;

  }
   // 每隔一秒，显示值减1; 渲染倒计时时钟
  that.setData({
   clock:dateformat(total_second - 1)
  });

   if (total_second == 0) {
    that.setData({
     // micro_second: "",
     clock:"时间到"
    });
    clearTimeout(micro_timer);
    return ;
   }  

 if (micro_second_current <= 0) {
  micro_second_current = micro_second_init;
 }
 micro_timer = setTimeout(function(){
  that.setData({
   micro_second: micro_second_current - 1
  });
  micro_second_current--;
  // 放在最后++，不然时钟停止时还有10毫秒剩余
  loop_index ++;
  countdown4micro(that);
 }
 ,10)
}

Like this In this way, milliseconds and hours, minutes and seconds are rendered separately. Once again, the program is more readable. dateformat operates on milliseconds and does not accept seconds. At the same time, it also saves the calculation of 100 calculations for 1 second

/** 
 * 需要一个目标日期，初始化时，先得出到当前时间还有剩余多少秒
 * 1.将秒数换成格式化输出为XX天XX小时XX分钟XX秒 XX
 * 2.提供一个时钟，每10ms运行一次，渲染时钟，再总ms数自减10
 * 3.剩余的秒次为零时，return，给出tips提示说，已经截止
 */

// 定义一个总毫秒数，以一分钟为例。TODO，传入一个时间点，转换成总毫秒数
var total_micro_second = 2 * 1000;

/* 毫秒级倒计时 */
function countdown(that) {
   // 渲染倒计时时钟
   that.setData({
     clock:dateformat(total_micro_second)
   });

   if (total_micro_second <= 0) {
     that.setData({
       clock:"已经截止"
     });
     // timeout则跳出递归
     return ;
   }  
   setTimeout(function(){
    // 放在最后--
    total_micro_second -= 10;
    countdown(that);
  }
  ,10)
}

// 时间格式化输出，如3:25:19 86。每10ms都会调用一次
function dateformat(micro_second) {
   // 秒数
   var second = Math.floor(micro_second / 1000);
   // 小时位
   var hr = Math.floor(second / 3600);
   // 分钟位
   var min = Math.floor((second - hr * 3600) / 60);
   // 秒位
  var sec = (second - hr * 3600 - min * 60);// equal to => var sec = second % 60;
  // 毫秒位，保留2位
  var micro_sec = Math.floor((micro_second % 1000) / 10);
  return hr + ":" + min + ":" + sec + " " + micro_sec;
}

Page({
  data: {
    clock: ''
  },
  onLoad: function() {
    countdown(this);
  }
});

After the above optimization, the code amount is reduced by half, and the operating efficiency is also high.

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