微信小程序 常用函数

1. 获取本周日期

note：上周日到这周六的日期
result: getWeeks()接收参数为时间格式，返回的是关于日期的一个数组 [2019-02-17,2019-02-18,…]
getDates() 返回日期的数组[17,18,19…]

  const UTIL = require('../../../utils/util.js');getDates() {let nowDate = new Date()let timesStamp = nowDate.getTime();let currenDay = nowDate.getDay();let dates = [];// 减去的一是为了获取包括上周日的时间数组for (var i = 0; i < 7; i++) {dates.push(new Date(timesStamp + 24 * 60 * 60 * 1000 * (i - (currenDay + 6) % 7 - 1)).getDate());}return dates},getWeeks(nowDate) {let nowDate = new Date()let timesStamp = nowDate.getTime();let currenDay = nowDate.getDay();let weekDates = [];for (var i = 0; i < 7; i++) {weekDates.push(UTIL.timeStampToYMD(timesStamp + 24 * 60 * 60 * 1000 * (i - (currenDay + 6) % 7 - 1)));}return weekDates},  

引用中的timeStampToYMD时间戳转化成yyyy-mm-dd格式函数:

	const timeStampToYMD = timeStamp => {var date = new Date(timeStamp);return formatTime(date).slice(0, formatTime(date).indexOf(' ')).replace(/\//g, '-');}const formatTime = date => {const year = date.getFullYear()const month = date.getMonth() + 1const day = date.getDate()const hour = date.getHours()const minute = date.getMinutes()const second = date.getSeconds()return [year, month, day].map(formatNumber).join('/') + ' ' + [hour, minute, second].map(formatNumber).join(':')}module.exports = {formatTime: formatTime,timeStampToYMD: timeStampToYMD}

2. 时间戳转化成年月日、分时秒

const formatTime = date => {const year = date.getFullYear()const month = date.getMonth() + 1const day = date.getDate()const hour = date.getHours()const minute = date.getMinutes()const second = date.getSeconds()return [year, month, day].map(formatNumber).join('/') + ' ' + [hour, minute, second].map(formatNumber).join(':')
}const formatNumber = n => {n = n.toString()return n[1] ? n : '0' + n
}
// 时间戳转化成 年月日
const timeStampToYMD = timeStamp => {var date = new Date(timeStamp);return formatTime(date).slice(0, formatTime(date).indexOf(' ')).replace(/\//g, '-');
}
// 时间戳转化成 分时秒
const timeStampToHMS = timeStamp => {var date = new Date(timeStamp);return formatTime(date).slice(formatTime(date).indexOf(' ') + 1);
}

2. checkbox 限制最多选择的个数

project 数组结构 为 [{“value”:“购物”;“isSelected”：false},{“value”:“逛街”;“isSelected”：false}]

  <checkbox-group wx:for="{{project}}" wx:key="{{index}}" bindchange="checkboxChange" data-index='{{index}}'><checkbox value='{{item.value}}' disabled="{{isMoreItem && !item.isSelected}}">{{item.value}}checkbox>checkbox-group>

isMoreItem初始值为false，当 totalNum 中选中的数组个数大于5个时，islimitItem为true 则新的未选择的不可选。

  // 选中checkboxChange(e) {let project = this.data.project;let index = e.currentTarget.dataset.index;project[index].isSelected = !project[index].isSelected;this.setData({project: project})let totalNum = project.filter((value)=>{return value.isSelected}).lengthif (totalNum > 4) {wx.showToast({title: '最多不能超过5项',icon: 'none'})this.setData({islimitItem: true})} else {this.setData({islimitItem: false})}console.log("totalNum*****", totalNum, "islimitItem", this.data.islimitItem)},

4. //判断已经出生多少年、多少月、多少日

接收一个数组： birthday 格式为 2019-03-11
婴儿[0,2) 儿童 [2,12) 成人12以上 return 3,2,1

judgeAge(birthday) {let ageObj = {};let date = birthday.replace(/-/g, '/'); // 字符转化 兼容IOSlet birth = new Date(`${date} 00:00:00`) //拼接时间let now = new Date()let yearDiff = now.getFullYear() - birth.getFullYear()let monthDiff = now.getMonth() - birth.getMonth()let dayDiff = now.getDate() - birth.getDate()if (birth.getTime() > now.getTime()) {return false;}// 婴儿[0,2) 儿童 [2,12) 成人[12以上 return 3,2,1const babyYear = 2const adultYear = 12if (yearDiff == babyYear) {return this.currentDateResult(monthDiff, dayDiff, 3, 2)} else if (yearDiff == adultYear) {return this.currentDateResult(monthDiff, dayDiff, 2, 1)} else if (yearDiff > babyYear && yearDiff < adultYear) {return 2;} else {return yearDiff < babyYear ? 3 : yearDiff > adultYear ? 1 : 2;}},currentDateResult(monthDiff, dayDiff, oneResult, twoResult) {if (monthDiff == 0) {return dayDiff < 0 ? oneResult : twoResult;} else {return monthDiff < 0 ? oneResult : twoResult;}},

5. 小数点保留 位数

toFixed() 使用的是银行家舍入规则：四舍六入五取偶（又称四舍六入五留双）。
(0.015).toFixed(2); // 0.01 ,

// 保留n位小数并格式化输出（不足的部分补0）
var fomatFloat = function(value, n) {var f = Math.round(value*Math.pow(10,n))/Math.pow(10,n);var s = f.toString();var rs = s.indexOf('.');   if (rs < 0) {     s += '.';   } for(var i = s.length - s.indexOf('.'); i <= n; i++){s += "0";}return s;
}
//var num3 = fomatFloat(0.015, 2);  // 0.02

6. 清除为undefined的空数组

  // 移除未定义的数组removeEmptyArrayEle(arr) {for (var i = 0; i < arr.length; i++) {if (arr[i] == undefined) {arr.splice(i, 1);i = i - 1;}}return arr},

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