Why type typeof(array) in JavaScript is object not array?

Question

Either we check type of array or object it always print object in JavaScript. Why so?

let arr=[1,3,4];
let obj={1:"44",num:44};

console.log(typeof(arr)) //object
console.log(typeof(obj)) //object

Is there any way to see typeof(array) as array?

Answer 1

Try using the instanceof operator

const arr = [];
console.log(arr instanceof Array); // true

const obj = {};
console.log(obj instanceof Array); // false

Answer 2

Because an array is technically a type of object - just with certain abilities and behaviors, for instance additional methods like Array.prototype.push() and Array.prototype.unshift(). Arrays are regular objects where there is a particular relationship between integer-key-ed properties and the length property.

To determine whether you have an array specifically, you can use Array.isArray().

Answer 3

In JavaScript, almost everything is an Object.

It uses prototype chain to achieve inheritance.

you can just console.log( [] ) and see the prototype part to see that it inherit from objects.

Here is a simple way to make an your own Array.

function MyArray(){
Object.defineProperty(this, 'length', {
    value: 0,
    enumerable: false,
    writable: true,
    })
}

MyArray.prototype.push = function(elem){
    this[this.length] = elem
    this.length++
    return this.length
}


MyArray.prototype.isMyArray = function(instance){
    return instance instanceof MyArray
}


var arr = new MyArray()
arr.push(1)
arr.push(2)
arr.push(3)


console.log('instance', MyArray.prototype.isMyArray( arr ))
// instance true
console.log('object', typeof arr)
// object object