倒计时适用于很多场景，先mark下来，以备之后的一时之用吧
以下案例是24小时的倒计时
wxml：
view倒计时 {{countHour}}:{{countMinute}}:{{countSecond}}/viewjs：
data: { countDay: null, countHour: null, countMinute: null, countSecond: null,},onReady: function () { this.setData({ countDay: '00', countHour: '24', countMinute: '00', countSecond: '00', }); // 设置开始时间，1天=86400秒 var totalSecond = 86400 - 1; // 设置定时器 var timeInterval = setInterval(function () { // 天 var day = Math.floor(totalSecond / 3600 / 24); if (day 10) day = '0' + day; // 时 var hour = Math.floor((totalSecond - day * 3600 * 24) / 3600); if (hour 10) hour = '0' + hour; // 分 var minute = Math.floor((totalSecond - day * 3600 *24 - hour * 3600) / 60); if (minute 10) minute = '0' + minute; // 秒 var second = totalSecond - day * 3600 * 24 - hour * 3600 - minute*60; if (second 10) second = '0' + second; this.setData({ countDay: day, countHour: hour, countMinute: minute, countSecond: second, }); totalSecond--; if (totalSecond 0) { clearInterval(timeInterval); wx.showToast({ title: '倒计时结束', }); this.setData({ countDay: '00', countHour: '00', countMinute: '00', countSecond: '00', }); } }.bind(this), 1000);},
