How does Javascript 'includes' method work when passing an object to array of objects

Question

Does includes method consider references too.

Eg:

let temp1 = [{a:5,b:3},{a:10,b:10}]
temp1.includes(temp1[0]) 
//returns true

let obj = {...temp1[0]}
temp1.includes(obj)
//returns false

Can someone please explain how includes method is working in this context

They must be the exact same object. obj === temp1[0] // false — evolutionxbox
– evolutionxbox, Commented Jul 23, 2020 at 13:30
I understand they are not the same object but how is includes method working when passing object having multiple key-value pairs. — bharys
– bharys, Commented Jul 23, 2020 at 13:37
In the first example, you are asking if temp1 contains an object, this object comes from temp1 so it's true. It's not comparing values or keys. — evolutionxbox
– evolutionxbox, Commented Jul 23, 2020 at 13:39

Catalyst · Accepted Answer · 2020-07-23 16:25:29Z

2

When you use temp1[0] you are comparing it with the exact same object, which is its first item, so it will return true.

When you uses the spread operator (...temp1) you are cloning the object, so when you compare both objects they won't be the exact same objects, and it will return false.

edited Jul 23, 2020 at 16:25

Catalyst

1,0182 gold badges12 silver badges19 bronze badges

answered Jul 23, 2020 at 13:33

alfouz

1063 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

bharys Over a year ago

includes compares values in an array, so if we pass objects which has keys does it compare key-value pairs. I wanted to know how includes work when objects are passed.

Catalyst Over a year ago

@bhasuru, no, it doesn't compare key-values, it compares between the address of the object in memory.

Collectives™ on Stack Overflow

How does Javascript 'includes' method work when passing an object to array of objects

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related