ES7-Es8 js代码片段

 ?1 function noRun(){ ?2 ????// es6的Generator函数异步 ?3 ????function* a(){ ?4 ????????yield console.log(1) ?5 ????????yield console.log(2) ?6 ????} ?7 ????var aa = a() ?8 ????aa.next() ?9 ????aa.next() 10 ?11 ????// es8的asyns/await异步 12 ????const timeout = async ms => { 13 ????????await new Promise((resolve) => { 14 ????????setTimeout(resolve, ms); 15 ????????}); 16 ????} 17 ?18 ????async function asyncP(value, ms, ms2) { 19 ????????// 顺序执行 20 ????????await timeout(ms); 21 ????????console.log(value); 22 ????????await timeout(ms2); 23 ????????console.log(ms2); 24 ?25 ????????// 并行执行 26 ????????await Promise.all([ 27 ????????????timeout(ms), 28 ????????????timeout(ms2) 29 ????????]); 30 ????} 31 ????asyncP(‘hello world‘, 5000, 3000); 32 ?33 ?34 ????/** 35 ?????* ES7 求幂运算符** 36 ?????* 在ES5中 == Math.pow(n,m) 37 ?????*/ 38 ????console.log(3**2) // 9 39 ?40 ????/** ?41 ?????* ES7 Array.prototype.includes(n, idx)方法 42 ?????* n是要查找内容，idx是开始查找的下标 43 ?????* ( 类似indexOf()方法 ) 44 ????*/ 45 ????let arr = [‘react‘, ‘angular‘, ‘vue‘]; 46 ????console.log(arr.includes(‘react‘)) ?// true 47 ????console.log(arr.includes(‘react‘, 1)) ?// false 48 ?49 ????/** 50 ?????* ES8 Object 51 ?????* ES8 Object.entries() 方法 52 ?????* 将某个对象的可枚举属性与值按照二维数组的方式返回 53 ?????* 如果对象的key值是数字，则返回值会对key值进行排序，返回的是排序后的结果 54 ?????*/ 55 ????Object.entries({ one: 1, two: 2 }) ???//[[‘one‘, 1], [‘two‘, 2]] 56 ????Object.entries([1, 2]) ???????????????//[[‘0‘, 1], [‘1‘, 2]] 57 ????// key为数字 58 ????Object.entries({ 3: ‘a‘, 4: ‘b‘, 1: ‘c‘ }) ???//[[‘1‘, ‘c‘], [‘3‘, ‘a‘], [‘4‘, ‘b‘]] 59 ????// ES6解构方式结合运用 60 ????let obj = { one: 1, two: 2 }; 61 ????for (let [k,v] of Object.entries(obj)) { 62 ????????console.log(`${k}: ${v}`); 63 ????} 64 ?65 ????/** 66 ?????* ES8 Object 67 ?????* ES8 Object.values() 方法 68 ?????* 只返回自己的键值对中属性的值 69 ?????* 顺序规则与Object.entries()一致 70 ?????*/ 71 ????Object.values({ one: 1, two: 2 }) ???????????//[1, 2] 72 ????Object.values({ 3: ‘a‘, 4: ‘b‘, 1: ‘c‘ }) ???//[‘c‘, ‘a‘, ‘b‘] 73 ?74 ????/** 75 ?????* ES8 Object 76 ?????* ES8 Object.getOwnPropertyDescriptors(‘参数‘, 可选-‘属性‘) 方法 77 ?????* 返回目标对象中所有属性的属性描述符，该属性必须是对象自己定义的，不能是从原型链继承来的 78 ?????*/ 79 ????let obj = { 80 ????????id: 1, 81 ????????name: ‘test‘, 82 ????????get gender() { 83 ??????????console.log(‘gender‘) 84 ????????}, 85 ????????set grade(g) { 86 ??????????console.log(g) 87 ????????} 88 ????} 89 ????Object.getOwnPropertyDescriptors(obj, ‘id‘) 90 ????//输出结果为： 91 ????// { 92 ????// ????id: { 93 ????// ????configurable: true, 94 ????// ????enumerable: true, 95 ????// ????value: 1, 96 ????// ????writable: true 97 ????// ????} 98 ????// } 99 ????100 101 ????/**102 ?????* ES8 String103 ?????* ES8 字符串填充：padStart(num, ‘‘)和padEnd(num, ‘‘)104 ?????* 函数通过填充字符串的首尾部来保证字符串达到固定的长度105 ?????*/106 ????‘JavaScript‘.padStart(8, ‘Hi‘) ????//‘JavaScript‘107 ????‘JavaScript‘.padStart(10, ‘Hi‘) ???//‘JavaScript‘108 ????‘JavaScript‘.padStart(12, ‘Hi‘) ???//‘HiJavaScript‘109 ????‘JavaScript‘.padStart(13, ‘Hi‘) ???//‘HiHJavaScript‘110 ????‘JavaScript‘.padStart(12) ?????????//‘ ?JavaScript‘111 112 ????/**113 ?????* ES8 Function114 ?????* ES8 函数参数列表与调用中的尾部逗号115 ?????* 该特性允许我们在定义或者调用函数时添加尾部逗号而不报错。116 ?????*/117 ????let foo = function (a,b,c,) {118 ????????console.log(‘a:‘, a)119 ????????console.log(‘b:‘, b)120 ????????console.log(‘c:‘, c)121 ????}122 ????foo(1, 3, 4, )123 }