ES6解构

ES6解构

1、解构对象案例

                var obj = {a:"1",b:"2"}
                const {a,b}=obj
                console.log(a)//1
                console.log(b)//2

                var obj = {a:"1",b:"2"}
                const {c,b}=obj
                console.log(c)//undefined
                console.log(b)//2

                var obj = {a:"1",b:"2"}
                const {c="6",b}=obj
                console.log(c)//6
                console.log(b)//2

                var obj = {a:"1",b:"2",c:"3",d:"4"}
                const {a,b,...z} = obj
                console.log(a)//1
                console.log(b)//2
                console.log(z)//{c:3,d:4}
                console.log(z.c+"+++"+z.d)//3+++4

2、解构方法案例

                var obj = {
                    hello:function(){console.log("aaa")}
                    }
                const {hello}=obj
                hello()//控制台输出字符串aaa

3、解构数组案例

                var arr = ["hello","world"]
                var arr1 = ["a"]
                var arr2 = ["bb"]
                const res=[...arr,...arr1,...arr2]
                console.log(res)//["hello","world","a","bb"]

                var a=[{aa:1,bb:"2"},{cc:"3",dd:"4"}]
                var b=[{ee:5,ff:"6"},{gg:"7",hh:"8"}]
                const [c,...d]=[...a,...b]
                console.log(JSON.stringify(c))
                console.log(JSON.stringify(d))

注意：解构数组必须用数组承接

                var a=[{aa:1,bb:"2"},{cc:"3",dd:"4"}]
                var b=[{ee:1,ff:"2"},{gg:"3",hh:"4"}]
                console.log(JSON.stringify(a))
                console.log(JSON.stringify(b))
                console.log(JSON.stringify([...a,...b]))
                console.log(JSON.stringify(...a))//在json.stringify下打印异常
                console.log(JSON.stringify([...a]))

扩展操作符只能用于可迭代对象，非可迭代对象会报错

补充：以上都是单层解构，如果是嵌套对象解构必须写成嵌套格式，比如：

let arr = ['a','b',['c','d']]
let [name,,[other]] = arr
console.log(name)//a
console.log(other)//[c,d]
arr[2][0] = 123
console.log(other)//[c,d]

//解构的最里层值必须是单层对象
let obj = {"a":1,"b":{"c":2,"d":{"e":111,"f":222}}}
let {a,b:{c,d}} = obj
console.log(a)//1
console.log(b)//undefined
console.log(c)//2
console.log(d) //{"e":111,"f":222}