ES5 & ES6 基础

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("2018-12-12");
let [x, y] = [1, 2, 3]; // x = 1, y = 2

let e = 50, f = 60;
[e, f] = [f, e];
console.log(e, f); //60,50

//Default
function findArtist(name='lu', age='26') {
//todo
}//Rest
function f(x, ...y) {
// y is an really Array
return 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 sum = (num1, num2) => { return num1 + num2; }
sum(1,2);
// return 3

// 等同于
var sum = function(num1, num2) {
return num1 + num2;
};

//按需输出0~10，闭包下
for (var i = 0; i < 10; ++i) {
setTimeout((i)=> {console.log(i)}, 0,i);
}

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

// return a b c
for (var n of ['a','b','c']) {
console.log(n);
}

function* helloWorldGenerator() {
yield 'hello';
yield 'world';
return 'ending';
}
var hw = helloWorldGenerator();

//代码没测试
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; //true// Maps
var m = new Map();
m.set("hello", 42);
m.set(s, 34);
m.get(s) == 34; //true//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

//数值的扩展
Number.EPSILON
Number.isInteger(Infinity) // false
Number.isNaN("NaN") // falseMath.acosh(3) // 1.762747174039086双曲函数方法
Math.hypot(3, 4) // 5平方和的平方根
Math.imul(Math.pow(2, 32) - 1, Math.pow(2, 32) - 2) //

//字符串的扩展
"abcde".includes("cd") // true
"abc".repeat(3) // "abcabcabc"

//数组的扩展
Array.from(document.querySelectorAll('*')) // Returns a real Array
Array.of(1, 2, 3) // [1,2,3] 将一组值转换为数组[0, 0, 0].fill(7, 1) // [0,7,7]
[1, 2, 3].find(x => x == 3) //
[1, 2, 3].findIndex(x => x == 2) //
[1, 2, 3, 4, 5].copyWithin(3, 0) // [1, 2, 3, 1, 2]
["a", "b", "c"].entries() // 遍历键值对[0, "a"], [1,"b"], [2,"c"]
["a", "b", "c"].keys() // 遍历键名 0, 1, 2
["a", "b", "c"].values() // 遍历键值 "a", "b", "c"

//对象的新增方法

const target={a:1};
const source1 = { b: 2 };
Object.assign(target, source1, {});//{a: 1, b: 2}
//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!';

(function () {
//proxy代理
const data = {
text2: '123'
}
const input = document.getElementById('app2-input');
const app2Text = document.querySelector('.app2-text'); const handler = {
//监控数据变化
set: function (target, prop, value) {
if (prop == 'text2') {
target[prop] = value; // 更新值
//以下更新视图
app2Text.innerHTML = value;
input.value = value;
return true;
} else {
return false;
}
}
}
let app2 = new Proxy(data, handler); //构造proxy对象 input.addEventListener('input', function (e) {
app2.text2 = e.target.value;
}, false)
}());

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 rejected
fakeAjax().then(function () {
console.log('success');
},function () {
console.log('fail');
});