var obj = {    // __proto__    __proto__: theProtoObj,    // Shorthand for ‘handler: handler’    handler,    // Method definitions    toString() {    // Super calls    return "d " + super.toString();    },    // Computed (dynamic) property names    [ ‘prop_‘ + (() => 42)() ]: 42};

let singer = { first: "Bob", last: "Dylan" };let { first: f, last: l } = singer; // 相当于 f = "Bob", l = "Dylan"let [all, year, month, day] =  /^(\d\d\d\d)-(\d\d)-(\d\d)$/.exec("2015-10-25");let [x, y] = [1, 2, 3]; // x = 1, y = 2

//Defaultfunction findArtist(name=‘lu‘, age=‘26‘) {    ...}//Restfunction f(x, ...y) {  // y is an Array  return x * y.length;}f(3, "hello", true) == 6//Spreadfunction f(x, y, z) {  return x + y + z;}// Pass each elem of array as argumentf(...[1,2,3]) == 6

var name = "Bob", time = "today";`Hello ${name}, how are you ${time}?`// return "Hello Bob, how are you today?"

for (var n of [‘a‘,‘b‘,‘c‘]) {  console.log(n);}// 打印a、b、c

class Artist {    constructor(name) {        this.name = name;    }    perform() {        return this.name + " performs ";    }}class Singer extends Artist {    constructor(name, song) {        super.constructor(name);        this.song = song;    }    perform() {        return super.perform() + "[" + this.song + "]";    }}let james = new Singer("Etta James", "At last");james instanceof Artist; // truejames instanceof Singer; // truejames.perform(); // "Etta James performs [At last]"

// lib/math.jsexport function sum(x, y) {  return x + y;}export var pi = 3.141593;// app.jsimport * as math from "lib/math";alert("2π = " + math.sum(math.pi, math.pi));// otherApp.jsimport {sum, pi} from "lib/math";alert("2π = " + sum(pi, pi));Module Loaders:// Dynamic loading – ‘System’ is default loaderSystem.import(‘lib/math‘).then(function(m) {  alert("2π = " + m.sum(m.pi, m.pi));});// Directly manipulate module cacheSystem.get(‘jquery‘);System.set(‘jquery‘, Module({$: $})); // WARNING: not yet finalized

// Setsvar s = new Set();s.add("hello").add("goodbye").add("hello");s.size === 2;s.has("hello") === true;// Mapsvar m = new Map();m.set("hello", 42);m.set(s, 34);m.get(s) == 34;//WeakMapvar wm = new WeakMap();wm.set(s, { extra: 42 });wm.size === undefined// Weak Setsvar ws = new WeakSet();ws.add({ data: 42 });//Because the added object has no other references, it will not be held in the set

Number.EPSILONNumber.isInteger(Infinity) // falseNumber.isNaN("NaN") // falseMath.acosh(3) // 1.762747174039086Math.hypot(3, 4) // 5Math.imul(Math.pow(2, 32) - 1, Math.pow(2, 32) - 2) // 2"abcde".includes("cd") // true"abc".repeat(3) // "abcabcabc"Array.from(document.querySelectorAll(‘*‘)) // Returns a real ArrayArray.of(1, 2, 3) // Similar to new Array(...), but without special one-arg behavior[0, 0, 0].fill(7, 1) // [0,7,7][1, 2, 3].find(x => x == 3) // 3[1, 2, 3].findIndex(x => x == 2) // 1[1, 2, 3, 4, 5].copyWithin(3, 0) // [1, 2, 3, 1, 2]["a", "b", "c"].entries() // iterator [0, "a"], [1,"b"], [2,"c"]["a", "b", "c"].keys() // iterator 0, 1, 2["a", "b", "c"].values() // iterator "a", "b", "c"Object.assign(Point, { origin: new Point(0,0) })

var target = {};var handler = {  get: function (receiver, name) {    return `Hello, ${name}!`;  }};var p = new Proxy(target, handler);p.world === ‘Hello, world!‘;

var key = Symbol("key");var key2 = Symbol("key");key == key2  //false

function fakeAjax(url) {  return new Promise(function (resolve, reject) {    // setTimeouts are for effect, typically we would handle XHR    if (!url) {      return setTimeout(reject, 1000);    }    return setTimeout(resolve, 1000);  });}// no url, promise rejectedfakeAjax().then(function () {  console.log(‘success‘);},function () {  console.log(‘fail‘);});