es6解耦、模块化、promise

1、a.js文件

const hello = {
    name:"zhangsan",
    sex:"男",
    eat(){
        console.log("是个吃货");
    }
}
export default hello;
export let a = "Hello JS";

2、b.js

import {a} from './a.js'
import b from './a.js'

console.log(a);
b.eat();

3、运行

node b.js

4、Promise

new Promise((resolve, reject) => {
    setTimeout(() => {
        console.log('山东省')
        resolve('山东省')
    }, 2000)

}).then(res => {
    console.log('这是第二个异步任务')
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log(res + '日照市')
            resolve(res + '日照市')
        }, 2000)
    })
}).catch(err => {
    console.log(err)
})