JS解构赋值_代码007(未授权)

本文介绍: 解构赋值语法是一种 Jav a script 表达式。通过解构赋值，可以将属性/值从对象/数组中取出，赋值给其他变量。本文将讨论解构赋值的作用与其用法。

解构赋值语法是一种 Jav a script 表达式。通过解构赋值，可以将属性/值从对象/数组中取出，赋值给其他变量。本文将讨论解构赋值的作用与其用法。

const arr = ["孙悟空","猪八戒","沙和尚"]
let a,b,c;

a= arr[0];
b= arr[1];
c= arr[2];
console.log(a,b,c);

[a,b,c]=["孙悟空","猪八戒","沙和尚"]
//表示数组的第一个元素赋值给第一个变量，第二个赋值给第二个变量，以此类推
console.log(a,b,c);

arr = ['孙','悟','空']
let [d,e,f]= arr;
console.log(d,e,f);

 let [g,h,i,j]=[1,2,3];

console.log(g,h,i,j);

let a, b;

[a=5, b=7] = [1];
console.log(a); // 1
console.log(b); // 7

let [n1,n2,...n3]=[1,2,3,4,5,6,7]//...获取剩余参数
console.log(n1,n2,n3)

let a1 = 10;
let a2 =20;

let temp =a1;
a1 = a2;
a2=temp;
//这个是我们常规的操作
[a1,a2]=[a2,a1];//这样的解构能实现交换
//表达式左边与右边表示的意义不一样，左边表示的是变量，右边才表示的是值，所以可以通过这种方式实现变量值交换

const arr1 = ["孙悟空","猪八戒"]
[arr1[0],arr[1]]=[arr1[1],arr[0]]//完成两个数组元素交换变量

function f() {
  return [1, 2];
}

let a, b;
[a, b] = f();
console.log(a); // 1
console.log(b); // 2

const arr3 = [[1,2,3],[4,5,6]];
console.log(arr3)
//    假如我们要解构一个二维数组
let [[num1,num2,num3],[num4,num5,num6]]=arr3
//将num1-6分别对应二维数组的六个元素
arr4=[]
[[num1,num2,num3],arr4]=arr3//将num1,num2,num3为1，2，3，arr4为[4,5,6]

const obj = {name:'qb',age:19,gender:'男'};
let {age,name,gender} = obj;
console.log(name,age,gender);

 let {address} = obj;
console.log(address)//undefined

let {name:a,age:b,gender:c} = obj;
console.log(a,b,c)

const metadata = {
  title: 'Scratchpad',
  translations: [
    {
      locale: 'de',
      localization_tags: [],
      last_edit: '2014-04-14T08:43:37',
      url: '/de/docs/Tools/Scratchpad',
      title: 'JavaScript-Umgebung'
    }
  ],
  url: '/en-US/docs/Tools/Scratchpad'
};

let {
  title: englishTitle, // rename
  translations: [
    {
       title: localeTitle, // rename
    },
  ],
} = metadata;

console.log(englishTitle); // "Scratchpad"
console.log(localeTitle);  // "JavaScript-Umgebung"

var people = [
  {
    name: 'Mike Smith',
    family: {
      mother: 'Jane Smith',
      father: 'Harry Smith',
      sister: 'Samantha Smith'
    },
    age: 35
  },
  {
    name: 'Tom Jones',
    family: {
      mother: 'Norah Jones',
      father: 'Richard Jones',
      brother: 'Howard Jones'
    },
    age: 25
  }
];

for (var {name: n, family: {father: f}} of people) {
  console.log('Name: ' + n + ', Father: ' + f);
}

// "Name: Mike Smith, Father: Harry Smith"
// "Name: Tom Jones, Father: Richard Jones"