var obj = {// __proto____proto__: theProtoObj,// Shorthand for ‘handler: handler’handler,// Method definitionstoString() {// Super callsreturn "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

//Default
function findArtist(name='lu', age='26') {...
}//Rest
function f(x, ...y) {// y is an Arrayreturn x * y.length;
}
f(3, "hello", true) == 6//Spread
function f(x, y, z) {return x + y + z;
}
// Pass each elem of array as argument
f(...[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; // true
james instanceof Singer; // truejames.perform(); // "Etta James performs [At last]"

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

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

Number.EPSILON
Number.isInteger(Infinity) // false
Number.isNaN("NaN") // falseMath.acosh(3) // 1.762747174039086
Math.hypot(3, 4) // 5
Math.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 Array
Array.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 XHRif (!url) {return setTimeout(reject, 1000);}return setTimeout(resolve, 1000);});
}// no url, promise rejected
fakeAjax().then(function () {console.log('success');
},function () {console.log('fail');
});