vue{{}}拼接字符串和换行符方式

const Utils = {
	// 反转字符串
    reverse = str => str.split('').reverse().join(''),
	// 是否是字符串
	isString = (value)=> Object.prototype.toString.call(value) === "[object String]",
	// 是否是布尔值
	isBoolean = (value)=> Object.prototype.toString.call(value) === "[object Boolean]",
	// 是否是数字
	isNumber = (value)=> Object.prototype.toString.call(value) === "[object Number]",
	// 是否是Underfined
	isUndefined = (value)=> Object.prototype.toString.call(value) === "[object Undefined]",
	// 是否是null
	isNull = (value)=> Object.prototype.toString.call(value) === "[object Null]",
	// 是否是NaN
	isNaN = (value)=> Number.isNaN(value),
	// 是否是对象
	isObject = (value)=> Object.prototype.toString.call(value) === "[object Object]",
	// 是否是函数
	isFunction = (value)=> Object.prototype.toString.call(value) === "[object Function]",
	// 是否是数组
	isArray = (value)=> Object.prototype.toString.call(value) === "[object Array]",
	// 获取变量类型
	getType = (value) => Object.prototype.toString.call(value),
	// Date 对象中获取时间
	timeDate = date => date.toTimeString().slice(0, 8),
	// 数字的奇偶数判断
	isEven = num => num % 2 === 0,
	// 判断当前日期是一年中的第几天
	dayOfYear = (date) => Math.floor((date - new Date(date.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24),
	// 计算两个日期之间的间隔时间
	dayDif = (date1, date2) => Math.ceil(Math.abs(date1.getTime() - date2.getTime()) / 86400000),
	// 滚动至页面顶部
	goToTop = () => window.scrollTo(0, 0),
	// 检查元素是否处于聚焦状态
	elementIsInFocus = (el) => (el === document.activeElement),
	// 检查当前用户是否是苹果设备
	isAppleDevice = /Mac|iPod|iPhone|iPad/.test(navigator.platform),
	// 判断当前标签页是否为可视状态
	isBrowserTabInView = () => document.hidden,
	// 获取选中的文本
	getSelectedText = () => window.getSelection().toString(),
	// 检测是否是黑暗模式
	isDarkMode = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches,
	// 首字母大写
	capitalize = str => str.charAt(0).toUpperCase() + str.slice(1),
	// 将RGB颜色转化为十六进制
	rgbToHex = (r, g, b) => "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1),
	// 随机十六进制颜色
	randomHex = () => `#${Math.floor(Math.random() * 0xffffff).toString(16).padEnd(6, "0")}`,
	// 两个整数之间的随机整数
	random = (min, max) => Math.floor(Math.random() * (max - min + 1) + min),
	// 数组去重
	removeDuplicates = (arr) => [...new Set(arr)],
	// 判断数组是否为空
	isEmpty = arr => Array.isArray(arr) && arr.length === 0
};
 
export default Utils;

let arr = [1, 2, 3]
let newArr = [...arr]    //[1, 2, 3]
 
let obj = {a:1}
let newObj = {...a}    //{a:1}

let arr1 = [1, 2, 3];
let arr2 = [4, 5, 6]
let target2 = [...arr1, ...arr2]    //[1, 2, 3, 4, 5, 6]
 
let obj1 = {
    b: 1,
    c: 10
}
let obj2 = {
    a: 3,
    b: 5
}
let target1 = {...obj1,...obj2}    //{a: 3, b: 5, c: 10}

let a = [1,2,3,4,5,6]
let [c,...d] = a
console.log(c); // 1
console.log(d); // [2,3,4,5,6] 

//动态数据用${}表示
const info = `我的名字是：${person.username}, 性别：${person.sex}, 今年${person.age}岁了`;
//*** 模板字符串中，所有的空格、换行或缩进都会被保留在输出之中

//es5的常规写法
let ax = function (num){
    return num * 2;
}
//写法1
let ax2 = (num) => {
    return num * 2;
}
//写法2
let ax3 = (num) => num * 2
//写法3
let ax3 = num => num * 2
//多参数写法（多参数前面必须有括号）
let ax4 = (num,mun2) => num * mun2

every() 方法用于检测数组所有元素是否都符合指定条件（通过函数提供），如果全部满足条件，则返回true，只要有一个不满足，则会直接返回false，并且剩下的不再进行检测；
some()方法则和every()不同，只要有一个符合指定条件，就会返回true，并且剩下的不在进行检测，如果全部不通过则返回false
const ages = [32, 33, 16, 40];
const age = ages.some(function(el){
    return el>18
});
console.log(age)
//age:true

var arr = [3,9,4,3,6,0,9];
let sum = arr.reduce((prev,cur,index)=>{
    return prev + cur
},0)
console.log(sum)

let  arr = [
  { num: 1, val: 'tom', flag: 'add' },
  { num: 2, val: 'mary', flag: 'del'  }
]
console.log(arr.filter(item => item.num===2 ))

var arr = ['1','2',undefined, '3.jpg',undefined]
var newArr = arr.filter(item => item)
console.log(newArr)
 
var arr = ['1','2',null, '3.jpg',null]
var newArr = arr.filter(item => item)
console.log(newArr)
 
//空字符串里面不能包含空格
var arr = ['1','2','', '3.jpg','']
var newArr = arr.filter(item => item)
console.log(newArr)

var arr = ['10','12','23','44','42']
var newArr = arr.filter(item => item.indexOf('2')<0) 
console.log(newArr)

var arr = [1, 2, 2, 3, 4, 5, 5, 6, 7, 7,8,8,0,8,6,3,4,56,2];
var arr2 = arr.filter((x, index,self)=>self.indexOf(x)===index)  
console.log(arr2); //[1, 2, 3, 4, 5, 6, 7, 8, 0, 56]

var arr=[1,2,1,'1',null,null,undefined,undefined,NaN,NaN]
let res=Array.from(new Set(arr));//{1,2,"1",null,undefined,NaN}
//or
let newarr=[...new Set(arr)]

let person = [
     {id: 0, name: "小明"},
     {id: 1, name: "小张"},
     {id: 2, name: "小李"},
     {id: 3, name: "小孙"},
     {id: 1, name: "小周"},
     {id: 2, name: "小陈"},  
];
 
let obj = {};
 
let peon = person.reduce((cur,next) => {
    obj[next.id] ? "" : obj[next.id] = true && cur.push(next);
    return cur;
},[]) //设置cur默认类型为数组，并且初始值为空的数组
console.log(peon);
// (4) [{…}, {…}, {…}, {…}]0: {id: 0, name: "小明"}1: {id: 1, name: "小张"}2: {id: 2, name: "小李"}3: {id: 3, name: "小孙"}length: 4__proto__: Array(0)
 

<van-field
  v-model="MeetingDescription"
  autosize
  type="textarea"
  placeholder="会议议程"
/>
 this.MeetingDescription = '会议议程：'+ '\n' + data.MeetingDescription