ES6解构

1、解构表达式传参

let User = {
            name : 'ghostwu',
            age : 22
        };

        function show( obj ){
            console.log( obj ); //obj其实就是User对象
            console.log( obj === User ); //true
            //函数中可以访问在参数中解构出来的变量
            console.log( name, age ); //ghostwu, 22
        } 
        show( { name, age } = User ); //表达式传值，整个表达式的值 取决于右边，所以把User传给了obj
        console.log( name, age ); //ghostwu, 22

2、解构数组

let arr = [ 10, 20, 30, 40 ];
// 数组用[]解构
 let [ one, two ] = arr;
 console.log( one, two ); //10 20

3、解构嵌套数组 

let arr = [ 10, [ 20, 30 ], 40 ];
console.log( arr[1][1] ); //30
let [ one, two, three, four ] = arr;
console.log( one, two, three, four ); //10 [20, 30] 40 undefined
[one, [ two, three ], four ] = arr; //前面不要let,否则会报重定义错误
console.log( one, two, three, four ); //10 20 30 40

4、解构中的不定参数(...)

   let arr = [ 10, 20, 30 ];
        let [ one, ...others ] = arr; 
        console.log( others.length ); //2
        console.log( one ); //10
        console.log( others[0] ); //20
        console.log( others[1] ); //30

 5、嵌套对象解构

let User = {
            name : 'ghostwu',
            age : 22,
            class : {
                group1 : {
                    one : '王超',
                    two : '马汉'
                },
                group2 : {
                    one : '张龙',
                    two : '赵虎'
                }
            }
        };
        //在User对象解构class, 在class中解构group1
        let { class : { group1 } } = User;
        console.log( group1.one ); //王超
        console.log( group1.two ); //马汉

        //在User对象解构class, 在class中解构group1, 在group1中解构one, two
        ({ class : { group1 : { one, two } } } = User);
        console.log( one, two ); //王超, 马汉

        //重命名group1 为 diyizu
        ({ class : { group1 : diyizu } } = User);
        console.log( diyizu.one ); //王超
        console.log( diyizu.two ); //马汉

        //three 赋默认值
        ({ class : { group1 : { one, two, three = '展昭' } } } = User);
        console.log( one, two, three );//王超,马汉,展昭