1. 常用及特殊

1. 字符串模板

2. 箭头函数

3. 变量

  let 与 var ,let定义在 for{ let name = "jay"; }  外面取不到,var 可以取得

  const 不可变

4. 展开

  function hello( name1, name2){
    console.log(name1, name2)
  }
  const arr = ['imooc' , 'woniu' ];
  1.) hello.apply(null,arr);  //  imooc  woniu
  2.) hello(...arr);   //  imooc  woniu

5. 对象扩展

  const obj = {name:'imooc', course:' react'};
  1.) Object.keys()
    console.log(Object.keys(obj));   // ['name', 'course']
  2.) Object.values()
    console.log(Object.values((obj));  // ['imooc' , 'react' ]
  3.) Object.entries()
    console.log(Object.entries(obj));  //[ ['name', 'course'] , ['imooc' , 'react' ] ]
  4.) 
    const name = 'imooc';
    const obj = {
      name:'hello'
    }
    const obj1 = {
      [name]:'hello'
    }
    console.log(obj);  // { name:'hello' }
    console.log(obj1);  // { imooc:'hello' }

  5.) 合并  
    const obj = { name:'imooc', course:'react' };
    const obj2 = {type:'IT', name:'woniu'};
    console.log({...obj, ...obj2});    // { name:'woniu', course:'react', type:'IT'}
      //同等于:
    console.log(Object.assign({}, obj, obj2));  // {name:'woniu', course:'react', type:'it'}
    console.log({...obj, ...obj2,date:'110'});    // {name:'woniu', course:'react', type:'IT', date:'110'}
   6.) 结构赋值
    const obj = { name:'imooc', course:'react' };
    const { name, course } = obj;
     console.log( name, course );    // imooc react

6. 数组 
  0.)解构
    let a = 3, b=6;
    [a , b] = [b , a];

  1.) 合并
    const arr2 = [1,2];
    const arr3 = [3,4];
    console.log([...arr2, ...arr3]);  // [1,2,3,4]

  2.)  结构赋值
    const arr = ['hello', 'imooc'];
    常规: let arg1 = arr[0];
        let arg2 = arr[1];
    现在: let [ arg1, arg2 ] = arr;
    console.log( arg1, arg2 );  // hello imooc

7. class 语法糖
  之前使用面向对象,定义函数定义它的propetype;
  现在class;
  1.)
    class MaApp{
      constructor() {
        this.name = 'imooc'
      }
      sayHello(){
        console.log(`hello ${this.name} !`)
      }
    }
    const app = new MyApp();
    app.sayHello();  //  hello imooc !

=====
8. 代码片段

  1.)所以数组是否通过测试
    [1,2,3,4,5].every( v => v>3);  //false
  2.)是否有元素通过测试
    [2,3,4,5].some(v=>v>3);  //true
  3.)过滤数组
    [1,2,3,4,5].filter(v=>v>3); // 4,5
  4.)去重
    const arr = [1,2,3,4,3,2];
    [...new Set(arr)];  //  [1,2,3,4]
  5.)获取对象的key
    const obj = {name:'WR',age:1};
    Object.keys({obj});  // [name,age]
  6.)获取对象里数据的数量
    Object.keys({name:'1', age:'11'}.length);
  7.)
    

 

posted @ 2018-05-27 02:05  大耳朵小虎  阅读(176)  评论(0编辑  收藏  举报