微信小程序倒计时组件开发

今天给大家带来微信小程序倒计时组件具体开发步骤:

先来看下最终效果:

git源:http://git.oschina.net/dotton/CountDown

分步骤-性子急的朋友,可以直接看最后那段代码。

wxml文件放个text

<text>second: {{second}} micro second:{{micro_second}}</text>

在js文件中调用

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);
        }
    });

运行验证下,从10走到1s,然后显示时间到。

于是继续将毫秒完善,注意毫秒的步长受限于系统的时间频率,于是我们精确到0.01s即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文件

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

如此,当秒级运行完毕时,毫秒级timer即clearTimeout,并将字本显示为'micro_second too'

再添加一个countdown4micro方法,使得显示剩余 0:3:19 89这样形式的倒数

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)
    }

如此这般,毫秒与时分秒是分别运行渲染的,再次改造,程序可读性更好。dateformat针对于毫秒操作,而不接受秒为数。同时还省却了计算100次为1s的运算

/**
     * 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);
        }
    });

经过如上优化,代码量减少一半,运行效率也高了。
---------------------
作者:第九程序
来源:CSDN
原文:https://blog.csdn.net/qq_38125123/article/details/73459963?utm_source=copy
版权声明:本文为博主原创文章,转载请附上博文链接!

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