Javascript [ ] concept

Rakesh Singh

8y1.1kWeb Development

Hi Everyone,

I need to understand the logic behind

console.log([]==[]) ;

the console will give the false for above but I do not know whats the logic behind this.

Please help me.

Thanks in Advance.

6 Replies

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Manav Pandya8y ago
Accepted answer
Hello

As per your sentence , you are comparing array

1 == :

It compares types of array that you have use

By default array declared is empty , and you are comparing with another empty array

That's why it shows false

2 === :

It compares both data type and also value to given them

So here in your example when im modify like :

console.log([] === []);

It shows output as : false

For example :

If you want to get type of anyone you can use
console.log(typeof []);
Output : object
In short you are comparing two object types

You can try by implementing simple example :
You will get output like : true
I hope it helps

Thanks
+3
B Patel8y ago
You didin't specified element positon in array. you are comparing empty array thats why it is returning False.
+1
Rakesh Singh8y ago
Thank you so much all.
0
Prakash Chasiya8y ago
Hello Rakesh;

Javascript arrays are objects and we can not simply use the == operator to compare the contents of the objects.

It will compare two objects if they are at same instance. Example given below:

var a;
var b;
if (a == b)
//true

if (null == null)
//true

if (undefined == undefined)
//true

You can also compare two objects by converting it to string, but the property for both objects will be the same as given below in example:

if(JSON.stringify(["a:a","b:b"])== JSON.stringify(["a:a","b:b"]))
//true

if(JSON.stringify([])== JSON.stringify([]))
//true

Hope this is easy to understand.

Thanks
+3
Sumit Chaudhary8y ago
var cars = ["Saab", "Volvo", "BMW"];
cars[0]==cars[0];

This is true because there is reference 'cars' but

[0]==[0]

there is no reference so that condatation could not true
+2
Cynthia Sathuragiri8y ago
Since [] creates a new instance of an array .So you are comparing one array object with the other array object and not with the contents of the array.Thus [] ==[] not equal and produces the result 'false'
+1