よく使うES 6/7の新特性

  const action = (num = 10)=> console.log(num)
  action()
  action(300)

  var name = "dukai"
  var age = 28
  var person = {name, age}

    //  
    const people = {
        name: 'dukai',
        age: 28
    }
    const { name, age } = people
    console.log(`${name}: ${age}`)
    //  
    const color = ['red', 'blue']
    const [first, second] = color
    console.log(first, second) 

    //   
    const color = ['red', 'yellow']
    const colorful = [...color, 'green', 'pink']
    console.log(colorful) //[red, yellow, green, pink]

    //   
    const child = { fist: 'a', second: 'b'}
    const parent = { ...child, third: 'c' }
    console.log(parent)

    //         
    //   
    const number = [1,2,3,4,5]
    const [one, ...part] = number
    console.log(one)  //1
    console.log(part) //2,3,4,5
    //   
    const user = {
        username: 'dk',
        gender: 'male',
        age: 28,
        address: 'Beijing'
    }
    const { username, ...part } = user
    console.log(part) //{ "gender": "male,  "age": 19,"address": "Beijing"}

    //      ，    ，**    **
    const first = {
        a: 1,
        b: 2,
        c: 6,
    }
    const second = {
        c: 3,
        d: 4
    }
    const total = { ...first, ...second }
    console.log(total) // { a: 1, b: 2, c: 3, d: 4 }

  1.   export default people   ，   import people   （     ）

  2.      ，       export default。      export。

  3.   export name  ，  import { name }  （       ）

  4.       ，    export default people,     export name    export age ，     import people, { name, age } 

  5.         n   export       ，           ，    import * as example

    setTimeout(function() {
      console.log(1)
    }, 0);

    new Promise(function executor(resolve) {
      console.log(2);
      for( var i=0 ; i<10000 ; i++ ) {
        i == 9999 && resolve();
      }
      console.log(3);
    }).then(function() {
      console.log(4);
    });

    console.log(5);

  async function reqApis(name) {
    var user = await req.getUser(name);
    var articles = await req.getArticles(user.id);
    // it is real article list here, but if returned it'll be a Promise 
    return articles;
  }
  // Becuase of the 'async' the result is Promise,
  // so we should use it like this
  reqApis('dukai').then((articles)=> {
    renderArticles(articles)
  })

  class Person {
    constructor(type) {
        this.type = type;
    }
    says(say) {
        console.log(`${this.type} says ${say}`);
    }
  }
  let person = new Person("person");
  person.says('hello'); 

  class Man extends Person {
    constructor(type, age) {
      super(type);
      this.type = type;
      this.age = age
    }

    says(say) {
      console.log(`${this.type} says ${say},  I'm ${this.age} years old.`);
    }
  }
  let jack = new Man("dukai", 28);
  jack.says('hello');