Set is adding duplicated object

Question

I'm trying create a set to insert objects avoiding duplicates.

When I do this:

const orgs = new Set();

set.add({
org_name: org.org_name,
relation_type: OrganisationRelationType.SELF,
related_org: org.org_name
});

set.add({
org_name: org.org_name,
relation_type: OrganisationRelationType.SELF,
related_org: org.org_name
});

I get the following output:

Set{
  {
    org_name: org.org_name,
    relation_type: OrganisationRelationType.SELF,
    related_org: org.org_name
  },
  {
    org_name: org.org_name,
    relation_type: OrganisationRelationType.SELF,
    related_org: org.org_name
  }
}

Instead of getting this:

Set{
  {
    org_name: org.org_name,
    relation_type: OrganisationRelationType.SELF,
    related_org: org.org_name
  }
}

How can I add to this Set avoiding duplicates in an efficient way?

captain-yossarian from Ukraine · Accepted Answer · 2022-07-27 07:21:37Z

1

In order to avoid duplications in Set you should take into account Set equality algorithm

Please be aware that two literal objects, even if they have same values, are not equal:

{ a: 42 } === { a: 42 } // false

Because references are different. However, in case of using references instead of literal objects, such equality will be true:

const foo = { a: 42 }

foo === foo // true

See this example:

const orgs = new Set();

const obj = {
    org_name: 1,
    relation_type: 2,
    related_org: 3
}

orgs.add(obj);

orgs.add(obj);

orgs.values() // 1

If two non primitive values in a set have same reference, second value will not be added

answered Jul 27, 2022 at 7:21

captain-yossarian from Ukraine

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