Array 判断是不是arr

instanceof 操作符

let arr = [];
arr instanceof Array// true

constructor 构造器

let arr = [];
arr.constructor === Array// true

isPrototypeOf Array原型链上

let arr = [];
Array.prototype.isPrototypeOf(arr) // ture

Object.getPrototypeOf

let arr = [];
Object.getPrototypeOf(arr) === Array.prototype // ture

Object.prototype.toString

let arr = [];
Object.prototype.toString.call(arr) === '[object Array]' // ture

Array.isArray

let arr = [];
Array.isArray(arr)