数组常用方法

数组解构赋值应用

// 交换变量
[a, b] = [b, a]
[o.a, o.b] = [o.b, o.a]
// 生成剩余数组
const [a, ...rest] = [...'asdf'] // a：'a'，rest: ["s", "d", "f"]

数组浅拷贝

const arr = [1, 2, 3]
const arrClone = [...arr]
// 对象也可以这样浅拷贝
const obj = { a: 1 }
const objClone = { ...obj }

数组合并

const arr1 = [1, 2, 3]
const arr2 = [4, 5, 6]
const arr3 = [7, 8, 9]
const arr = [...arr1, ...arr2, ...arr3]

数组去重

const arr = [1, 1, 2, 2, 3, 4, 5, 5]
const newArr = [...new Set(arr)]

数组取交集

const a = [0, 1, 2, 3, 4, 5]
const b = [3, 4, 5, 6, 7, 8]
const duplicatedValues = [...new Set(a)].filter(item => b.includes(item))
duplicatedValues // [3, 4, 5]

数组转对象

const arr = [1, 2, 3, 4]
const newObj = {...arr} // {0: 1, 1: 2, 2: 3, 3: 4}
const obj = {0: 0, 1: 1, 2: 2, length: 3}
// 对象转数组不能用展开操作符，因为展开操作符必须用在可迭代对象上
let newArr = [...obj] // Uncaught TypeError: object is not iterable...
// 可以使用Array.form()将类数组对象转为数组
let newArr = Array.from(obj) // [0, 1, 2]

数组常用遍历

检测数组所有元素是否都符合判断条件
const arr = [1, 2, 3, 4, 5]
const isAllNum = arr.every(item => typeof item === 'number')
检测数组是否有元素符合判断条件
const arr = [1, 2, 3, 4, 5]
const hasNum = arr.some(item => typeof item === 'number')