进行对字符串扩展，正则扩展，数值扩展，函数扩展，对象扩展，数组扩展。开发环境准备：编辑器（VS Code, Atom，Sublime）或者IDE（Webstorm）浏览器最新的Chrome字符串的扩展：模板字符串，部分新的方法，新的unicode表示和遍历方法：部分新的字符串方法padStart，padEnd，repeat，startsWith，endsWith，includes字符串的扩展：Unicode和UTF-16是什么和他们的关系用for-of遍历字符：模板字符串是什么：`dashucoding`const da = { name: 'dada', age: 12, say1: function() { console.log('da'); }, say2: function() { console.log('da'); }}da.say1();da.say2();'我叫'+ this.name.toUpperCase() + ',我今年' + this.age + '岁'// 模板字符串(`我叫${` Mr.${this.name.toUpperCase() }` },我今年${this.age}岁!`);const getList = function() { // ajax return{ status: true, msg: '获取成功', data: [{ id: 1, title: '入门', date: 'xxx' },{ id: 2, title: '入门', date: 'xx' },{ id: 3, title: '入门', date: 'x' }] }};const { status, msg, data: listData } = getList();if(status) { let arr = []; listData.forEach(function({data, title}){ arr.push( '<li>\ <span>' + title + '</span>' + '<span>' + data + '</span>' + '</li>' ); });arr.push( ` <li> <span>${title}</span> <span>${date}</span> </li> `)部分新方法：// padStart padEnd{ let str = '1'; let str1 = str.padStart( 3, 'da'); let str1 = str.padStart( 5, 'da'); // dadai console.log(str1); // dai}// let str2 = str.padEnd(3, 'da'); // ida// repeat{ console.log('i', repeat(5)); // i,i,i,i,i}function repeat(str, num) { return new Array(num+1).join(str);}console.log(repeat('i',3));// startsWith endsWith以什么什么开头，以什么结尾的{ const str = 'A d c'; cosole.log(str.startsWith('B')); // false cosole.log(str.startsWith('A SSS')); console.log(str.endsWith('c')); console.log(str.endsWith('A'));}// includes{ const str = 'A PD'; // if(str.indexOf('pr') !== -1) { if(~str.indexOf('PD')) { console.log('1'); } if(str.includes('PD')) { console.log('2'); }}for-of遍历字符串let str = 'abc';// es6 之前的遍历for(var i=0, len = str.length; i<len; i++){ console.log(str[i]); console.log(str.charAt(i));}// 转成数组后遍历var arrStr = Array.prototype.slice.call(str);console.log(arrStr);var arr = str.split('');const arr = [...str];const [...arr] = str;// for-of遍历字符串for(let word of str) { console.log(word);}let newStr = '';for(let word of str) { if(words.includes(word)) newStr += map[word];}console.log(newStr)unicode表示法：Unicode是一种标准，包括了字符串，编码方案等，它是为了解决传统的字符编码方案的局限而产生的，每种语言中的每个字符设定了统一并且唯一的二进制编码，以满足跨语言，跨平台进行文本转换，处理的要求。正则扩展：const regexp1 = /^a/g;const regexp2 = new RegExp('^a', 'g');const regexp3 = new RegExp(/a/g);console.log('abc'.match(regexp1));console.log('bd'.match(regexp1));console.log('aabbaaccaasld'.match(regexp3));构造函数的变化：const regexp5 = new RegExp(/a/giu, 'ig');数值扩展：新的进制表示法新的方法与安全数// Number.parseInt Number.parseFloatconsole.log(window.parseInt(1.23))// 1console.log(parseFloat('1.23'));// 1.23console.log(Number.parseInt(1.23));// 1console.log(Number.parseFloat(1.23));// 1.23// Number.isNaN Number.isFinite// isNaNconsole.log(Number.isNaN(NaN)); // trueconsole.log(Number.isNaN(-NaN)); // trueconsole.log(Number.isNaN(1)); // falseconsole.log(Number.isNaN('1')); // falseconsole.log(Number.isNaN(true)); // falsefunction isNaN(value) { return value !== value;}isFiniteconsole.log(Number.isFinite(Infinity));console.log(Number.isFinite(2/0));console.log(Number.isFinite(2/4));console.log(Number.isFinite(123));console.log(Number.isFinite('123'));console.log(Number.isFinite(true));console.log(Number.isFinite(NaN));函数扩展：默认参数，与扩展运算符结合，箭头函数函数参数的默认值：function add(a,b=1){ console.log(a,b);}add(1);function People({name, age = 38 } = {}){ console.log(name,age);};People();function People({name, age=30} = {name:1}) { console.log(name,age);};People()People({name: 3});结合扩展运算符（剩余参数。。。）function sum() { console.log(arguments); console.log(arguments instanceof Array); // false}sum(1,2,3,'23');function sum() { let args = Array.prototype.slice.call(arguments); console.log(args);}sum(2,3,32);// 结合扩展运算符（剩余参数...）function sum(...args) { // let args = Array.prototype.slice.call(arguments); // let args = [...arguments]; // let [...args] = arguments; console.log(args);}sum(1,23,3);function sum(...numbers) { return numbers.reduce(function(a,b) { return a+b; },0);}console.log(sum(1,2,3,4));箭头函数：const add1 = (a,b) => a+b;const add2 = function(a,b) { return a+b;}console.log(add1(2,3));console.log(add2(2,3));const pop = arr => void arr.pop();console.log(pop([2,3,4]));const log = () => { console.log(arguments);};log(1,2,3);const log = (...args) => { console.log(args);};log(1,2,3);const xiao = { name: 'da', say1: function() { console.log(this); }, say2: () => { console.log(this); }}xiao.say1();xiao.say2();部分新的方法和属性：// Object.is// === // +0 -0// NaNconsole.log(Object.is(+0, -0)); // falseconsole.log(+0 === -0); // trueconsole.log(Object.is(NaN,NaN)); // trueconsole.log(NaN === NaN); // falseconsole.log(Object.is(true,false)); // falseconsole.log(Object.is(true,true)); // trueObject.assignconst obj = Object.assign({a: 1}, {b: 2}, {c: 3}, {id:4, e:5});const obj = { a: 1, b: { c: 2 }};let newObj = Object.assign({a:3},obj);console.log(newObj.b.c);newObj.b.c = 100;console.log(obj.b.c);2100Object.keys// console.log(Object.keys(obj));// object.values// console.log(Object.values(obj));// Object.entries// console.log(Object.entries(obj));for(let key of Object.keys(obj)) { console.log(key);}// __proto__console.log({a: 1});Object.setPrototypeofconst obj1 = { a: 1};const obj2 = { b: 1}const obj = Object.create(obj1);console.log(obj.__proto__)Object.setPrototypeOf(obj,obj2);console.log(obj.__proto__);// Object.getPrototypeOfconst obj1 = {a:1};const obj = Object.create(obj1);console.log(obj.__proto__);console.log(Object.getPrototypeOf(obj));console.log(obj.__proto__ === Object.getPrototypeOf(obj));// superconst obj = {name: 'da'};const cObj = { say() { console.log(`my name is ${super.name}`); }}Object.setPrototypeOf(cObj.obj);cObj.say();数组的扩展和扩展运算符结合，新的方法：function da(a,b,c){ console.log(a); console.log(b); console.log(c);}da(...[12,3,4]);数组的新方法：Array.fromArray.ofArray.fillArray.includeskeys,values,entries,findfrom()方法将一个ArrayLike对象或者是Iterable对象转换成一个Arrayconst obj = { 0: 1, 1: 2, 2: 4, length: 3};console.log(Array.from(obj));const obj = { 0: 1, 1: '22', 2: false, length: 2};console.log(Array.from(obj, item => item * 2));Array.prototype.slice.call();[].slice.call();[...]Array.of合成组成console.log(Array.of(2,3,4));let arr = new Array(10).fill(0); // 10个元素都是0console.log([2,3,4].fill(0)); // [0,0,0]let arr = new Array(10).fill(0,0,3);Array.includesvar arr = [1,2,3,4];console.log(arr.includes(1));console.log(arr.includes(55));// keys 获取下标const arr = [0,1,8,3];console.log(arr.keys);for(let i of arr.keys()) { console.log(i);}// values 获取值for(let v of arr.values()) { console.log(v);}// entriesfor(let v of arr.entries()){ console.log(v);}for(let [i,v] of arr.entries()){ console.log(i,v);}const res = [1,2,3].find(function(value,index,arr){ console.log('value',value); console.log('index', index); console.log('arr',arr); return value % 2 === 0;});console.log(res);字符串，正则，数值，函数，对象，数组扩展。?? 不要忘记留下你学习的脚印 [点赞 收藏 评论]作者Info：【作者】：Jeskson【原创公众号】：达达前端小酒馆。【转载说明】：转载请说明出处，谢谢合作！~关于目前文章内容即涉及前端，PHP知识点，如果有兴趣即可关注，很荣幸，能被您发现，真是慧眼识英！也感谢您的关注，在未来的日子里，希望能够一直默默的支持我，我也会努力写出更多优秀的作品。我们一起成长，从零基础学编程，将 Web前端领域、数据结构与算法、网络原理等通俗易懂的呈现给小伙伴。分享 Web 前端相关的技术文章、工具资源、精选课程、热点资讯。若本号内容有做得不到位的地方（比如：涉及版权或其他问题），请及时联系我们进行整改即可，会在第一时间进行处理。请点赞！因为你们的赞同/鼓励是我写作的最大动力！欢迎关注达达的CSDN！这是一个有质量，有态度的博客
