解构赋值的用处

Posted 2021-09-29 水香木鱼

用处1：交换两个变量的值

let a = 10,b = 20; console.log([a,b] = [b,a]);

用处2：从函数返回多个值

function fn(){     return [1,2,3,4,5]; } var [a,b,c,d,e] = fn(); console.log(a,b,c,d,e);

用处3：函数参数的定义

function fn3([x,y,z]){     return x+y+z; } console.log(fn3([4,5,6]))

用处4：函数参数的默认值

function fn4([x=1,y=2,z=3]){     return x+y+z; }     console.log(fn4([4,5,6]))

用处5：提取JSON数据

var dataJson = {     "id":1,     "status":"ok",     "data":[1,2,3,4] }     var {id,status,data:arr} = dataJson; console.log(id,status,arr); //输出: 1 "ok" [1,2,3,4]

用处6：遍历Set、Map数据结构

var map = new Map(); map.set("first","hello"); map.set("second","world"); console.log(map); for(var [key,value] of map){     console.log(key+"is:"+value) }

用处7：输入模块的指定方法

var {sourceSort,sourceNumber} = require("soure-map")