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
}