ES6 中可以提升幸福度的小功能

let x = 1;let y = 2;[x, y] = [y, x]

// 返回一个数组function example(){  return [1, 2, 4];}let [a, b, c] = example() // 返回一个对象function example(){  return {    foo:1,    bar: 2  }}let {foo, bar} = example(); 或者 ( {foo, bar} = example() )

let jsonData = { id:42, status: "OK", data: [867, 5309]};let { id, status, data: number} = jsonData;

const { SourceMapConsumer, SourceNode } = require("source-map")

// 在 es5 中克隆数组var colors = [ 'red', 'green', 'blue' ];var clonedColors = colors.concat();console.log(clonedColors); // "[red, green, blue]"

let colors = [ 'red', 'green', 'blue' ]let [ ...clonedColors ] = colors;console.log(clonedColors); // "[red, green, blue]"

function eliminateDuplicates(items) {  return [...new Set(items)]}let numbers = [1, 2, 3, 3, 3, 4, 5];let noDuplicates = eliminateDuplicates(numbers );console.log(noDuplicates ); // [1,2,3,4,5]

var arra1 = [{ name: '小智', age: 26}]var arra2 = [{ name: '大智', age: 27}]arra1.push.apply(arra1, arra2)console.log(arra1)

// es5let person = function(name) { return {  getName: function() {   return name;  } }}('小智');console.log(person.getName()); // 小智

// es6let person = ((name) => { return {  getName: function() {   return name;  } }})('小智2');console.log(person.getName()); //小智

function throwEmptyError() {  throw new Error('参数不能为空');}function foo(mustBeParams = throwEmptyError() ){  return mustBeParams();}foo() // 参数不能为空

let lastName ='last name';let person = {  "first name": 'Nicholas',  [lastName]: 'Zakas'}console.log(person['first name']); // "Nicholas"console.log(person[lastName]); // Zakas

function request(options) { let defaultOptions = {  port: 8000,  type: 'get' } Object.assign(options,defaultOptions); console.log(options)}request({url: 'http://www.baidu.com'})

// 此处tap函数接受一个 vaule 并返回一个包含value 闭包函数,该函数被执行const tap = (value) => (fn) => ( typeof(fn) === 'function' && fn(value), console.log(value))

[1, 2 ,3, 4].forEach((a) => { tap(a)((a)=> {  console.log(a) })});#### 2) once 函数

const once = (fn) => {  let done = false;  return function () {    return done?undefined:((done=true),fn.apply(this,arguments))  }}const doPayment = once(()=>{ console.log('payment is done')})doPayment(); // payment is doneconsole.log(doPayment()); //undefined#### 3) 函数柯里化的应用

const loggerHelper = (mode, initialMessage, errorMessage, lineNo) => { if (mode === 'DEBUG') {  console.debug(initialMessage,errorMessage + 'at line:' + lineNo) } else if (mode === 'ERROR') {  console.error(initialMessage,errorMessage + 'at line:' + lineNo) } else if (mode === 'WARN') {  console.warn(initialMessage,errorMessage + 'at line:' + lineNo) } else  throw "Wrong mode"}

loggerHelper("ERROR", "ERROR At Stats.js", "Invalid argument passed", 23);

let curry = (fn) => { if (typeof fn !== 'function') {  throw Error('No function provided'); } return function curriedFn(...args) {  // 传入参数是否小于函数参数列表长度，  if (args.length < fn.length) {   return function() {    return curriedFn.apply(null, args.concat([].slice.call(arguments)));   }  }  return fn.apply(null, args) }} let errorLogger = curry(loggerHelper)("ERROR")("ERROR At Stats.js");let debugLogger = curry(loggerHelper)("DEBUG")("ERROR")("Debug At Stats.js");let warnLogger = curry(loggerHelper)("WARN")("Warn")("At Stats.js");// 用于错误errorLogger("Error message", 21)// 用于调试debugLogger('Debug message', 233)// 用于警告warnLogger("Warn message", 34);