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

//全部导入
import people from './example'

//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
//该模块的所有导出都会作为对象的属性存在
import * as example from "./example.js"
console.log(example.name)
console.log(example.age)
console.log(example.getName())

//导入部分
import {name, age} from './example'

// 导出默认, 有且只有一个默认
export default App

// 部分导出
export class App extend Component {};

5.class类的支持

Es6中添加了对class类的支持：

//定义class
class Animal(){
    //ES6中新型构造器
    constructor(name) {
        this.name = name;
    }
    //实例方法
    sayName() {
        console.log('My name is '+this.name);
    }
}

//类的继承
class Programmer extends Animal {
    constructor(name) {
    	//直接调用父类构造器进行初始化
        super(name);
    }
    program() {
        console.log("I'm coding...");
    }
}
//测试我们的类
var animal=new Animal('dummy'),
wayou=new Programmer('wayou');
animal.sayName();//输出 ‘My name is dummy’
wayou.sayName();//输出 ‘My name is wayou’
wayou.program();//输出 ‘I'm coding...’

6.for of

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