如何判断一个对象是否为数组-多种方式

1.Object.prototype.toString.call()

function isArray(obj) { if (typeof obj === 'object'){ return Object.prototype.toString.call(obj) === '[object Array]'; } return false; }

测试：

let arr = [1,2,3]; let num = 520; let res = isArray(arr); let res2 = isArray(num); console.log(res);//true console.log(res2);//false

2.Array.isArray

let arr = [1,2,3]; let num = 520; let res = Array.isArray(arr); let res1 = Array.isArray(num); console.log(res);//true console.log(res1);//false

3.判断原型对象是不是Array的原型对象

let arr = [1,2,3]; let obj = {num:520}; console.log(arr.__proto__ === Array.prototype);//true console.log(obj.__proto__ === Array.prototype);//false

4.instanceof

let arr = [1,2,3]; let obj = {num:520}; console.log(arr instanceof Array);//true console.log(obj instanceof Array);//false

5.xxx.constructor.name

let arr = [1,2,3]; let obj = {num:520}; console.log(arr.constructor.name);//Array function isArray(obj) { if (typeof obj === 'object'){ return obj.constructor.name === 'Array'; } return false; } let res = isArray(arr); let res1 = isArray(obj); console.log(res);//true console.log(res1);//false

6.Array.prototype.isPrototypeOf(arr)

let arr = [1,2,3]; console.log(Array.prototype.isPrototypeOf(arr));//true