How does JavaScript compare object passed in method as arguments?

Question

I saw interview question here in debugging section (first question).

function greet(person) {
  if (person == { name: 'amy' }) {
    return 'hey amy'
  } else {
    return 'hey arnold'
  }
}
greet({ name: 'amy' })

This is printing hey arnold.

I want to understand why this is happening? Any explanation or direction to resource would be much appreciated.

== will just do referential comparison. As these 2 are different objects, it won't be true. If you want to learn how to do deep comparison of objects refer to this post https://stackoverflow.com/questions/1068834/object-comparison-in-javascript — Mahendra Pratap, Aug 26 '19 at 19:20
Thank You @MahendraPratap for the link. I've better understanding now. — Nirav, Aug 26 '19 at 19:27

score 1 · Answer 1 · answered Aug 26 '19 at 19:19

1

objects are checked for equality by reference, not value.

{a: 1} === {a: 1} // returns false

answered Aug 26 '19 at 19:19

David Ko

score 1 · Answer 2 · answered Aug 26 '19 at 19:19

1

Objects are compared by reference, not by value. Two objects with the same properties and values are still different objects.

answered Aug 26 '19 at 19:19

Eric Lippert

1

I see. Completely forgot about check by reference. Thank You @eric-lippert. – Nirav Aug 26 '19 at 19:27

2 Answers2