【微信小程序开发】倒计时组件

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:

源码:http://download.csdn.net/download/acmdown/9931482

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

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

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

second: {{second}}s{{micro_second}}

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。

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