ES6 简单整理

1.变量声明 let 和 const

let与const 都是块级作用域，

• let

  function name(){ let age = 12; //age只在name()函数中存在 }

• const

  const name = 'tom' name = 'jack'//再次赋值会报错

2.字符串模板

• Es5

  //例1 var name = 'jack'; console.log('hello '+name) //例2 var msg = 'Hi
  man! '//以反斜杠用来换行

• Es6

  //例1 const name = 'jack' console.log('hello ${name}');//hello jack //例2 onst template = <div> <span>hello world</span> </div>

3.扩展的对象的功能

• Es5

  //例1 function people(name,age){ return { name:name age:age } } //例2 const people = { name : 'tom', getThisName:function(){ console.log(this.name) } }

• Es6

  //例1 function people(name,age){ return { name age } } //例2 const people = { name : 'tom', getThisName(){ console.log(this.name) } }

4.import 和 export

1//全部导入
2import people from './example'
3
4//有一种特殊情况，即允许你将整个模块当作单一对象进行导入
5//该模块的所有导出都会作为对象的属性存在
6import * as example from "./example.js"
7console.log(example.name)
8console.log(example.age)
9console.log(example.getName())
10
11//导入部分
12import {name, age} from './example'
13
14// 导出默认, 有且只有一个默认
15export default App
16
17// 部分导出
18export class App extend Component {};

5.class类的支持

Es6中添加了对class类的支持：

1//定义class
2class Animal(){
3    //ES6中新型构造器
4    constructor(name) {
5        this.name = name;
6    }
7    //实例方法
8    sayName() {
9        console.log('My name is '+this.name);
10    }
11}
12
13//类的继承
14class Programmer extends Animal {
15    constructor(name) {
16    	//直接调用父类构造器进行初始化
17        super(name);
18    }
19    program() {
20        console.log("I'm coding...");
21    }
22}
23//测试我们的类
24var animal=new Animal('dummy'),
25wayou=new Programmer('wayou');
26animal.sayName();//输出 ‘My name is dummy’
27wayou.sayName();//输出 ‘My name is wayou’
28wayou.program();//输出 ‘I'm coding...’
29

6.for of

1var someArray = [ "a", "b", "c" ];
2 
3for (v of someArray) {
4    console.log(v);//输出 a,b,c
5}