JavaScript – 解构赋值 Destructuring Assignment

Array Destructuring Assignment

old school

const items = [1, 2, 3];
const item1 = items[0];
const item2 = items[1];
const item3 = items[2];

一个一个从 array 拿出来, 再一个一个 assign 给每一个变量.

modern

const [item1, item2, item3] = [1, 2, 3];

一行里面做了 declare, assign, read from array. 3 个动作一气呵成.

get someone

const [, , value3] = [1, 2, 3];

with default value

const [v1] = []; // v1 = undefined
const [v1 = 'default value'] = []; // v1 = 'default value'
const [v1 = 'default value'] = ['value']; // v1 = 'value'

Object Destructuring Assignment

它和 Array 的用法差不多.

const person = { name: 'Derrick', age: 11 };
const { name, age } = person;

with alias 别名

const person = { name: 'Derrick', age: 11 };
const { name: newName, age: newAge } = person;
console.log(newName);
console.log(newAge);

name: newName 中间使用了分号

with default value

const { name = 'Derrick', age } = {};
// name = 'Derrick'
// age = undefined

标签：const,name,default,Assignment,age,JavaScript,value,解构,v1
来源： https://www.cnblogs.com/keatkeat/p/16229773.html