停用var 换用let const

let a = 20;
const b = 30;

类似php的直接引用值

let a="hello",c="world",op="tryES6!!";
const string = `${a}+${c}:::${op}`;
console.log(string);//hello+world:::tryES6!!

箭头函数

const fn = (a,b) => (a*60+30+b);
fn(3,5);//215

const foo = ()=>{
	const a=30;
	const b=60;
	return a+b;
}
foo();//90

const fx = () => {
	console.log("Hello ES6!");
}
fx();//Hello ES6!

两种主要用法

1. 直接返回值
2. 声明函数

默认值

function add(x=20,y=30){
	return x+y;
}
add();

解析结构

const props = {
	size : 1,
	src  : 'xxxx',
	mode : 'die'
}
const {size, src} = props;
console.log(size);//1

其实就是利用了一个结构来快速获取对象中的某个值，这样可以大量简写

展开运算符

const arr1 = [1,2,3];
const arr2 = [...arr1,4,5,6];//[1,2,3,4,5,6]

const obj1={a:10, b:20, c:30};
const obj2={...obj1, d:50, e:60};//{a: 10, b: 20, c: 30, d: 50, e: 60}

进阶：

const props = {
  size: 1,
  src: 'xxxx',
  mode: 'si'
}
const { size, ...others } = props;
console.log(others)
<button {...others} size={size}/>

利用展开运算符将可能出现的其他不定参数取出

Class!

class Person{
	constructor(name, age){
		this.name=name;
		this.age=age;
	}

	getName(){ return this.name;5}
}