Check if an object exist in an array in Angular 6

Question

I have an array of categories: this.categories

[ { "id": 6, "name": "categories.ladies_team" }, { "id": 2, "name": "categories.junior_team" }, { "id": 7, "name": "categories.master" }, { "id": 5, "name": "categories.ladies_single" }, { "id": 1, "name": "categories.junior" }, { "id": 3, "name": "categories.men_single" }, { "id": 4, "name": "categories.men_team" } ]

Now I have a new element:

const newCategory = {
    id: category.id,
    name: category.name
};

I would like to insert it if not present.

I tried:

if (!this.categories.includes(newCategory)) {
    this.categories.push(newCategory);
  }

but it is not working...

What am I doing wrong ?

Well, you need to define "not present", and then find if some() element of the array matches the predicate indicating that it's present — JB Nizet
– JB Nizet, Commented Jun 13, 2018 at 18:28

user184994 · Accepted Answer · 2018-06-13 18:27:58Z

25

Unfortunately, includes will not work unless it is the same instance. You will need to do something like;

if (!this.categories.some((item) => item.id == newCategory.id)) {
    this.categories.push(newCategory);
}

answered Jun 13, 2018 at 18:27

user184994

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1 Comment

Ravi Shankar Kota Over a year ago

some return true/false while find returns the found item in the array or undefined when item is not found. So some is really helpful just to know the existence of the item in array.

Anindyo Bose · Accepted Answer · 2019-05-30 10:21:54Z

5

The solution given by user184994 didn't worked for me, It was only fetching the first element. I tried like this which worked for me.

let data = this.categories.find(ob => ob.id === newCategory.id);
if(data === null){
 this.categories.push(newCategory);
}

answered May 30, 2019 at 10:21

Anindyo Bose

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1 Comment

Gobind Gupta Over a year ago

if an element is not found then data would be undefined rather then null.

Karthik Srinivasan · Accepted Answer · 2022-01-12 02:10:10Z

0

Anindyo Bose solution also not working. Replacing null check with undefined works for me.

let data = this.categories.find(ob => ob.id === newCategory.id);
 if(data === undefined){
      this.categories.push(newCategory);
}

answered Jan 12, 2022 at 2:10

Karthik Srinivasan

413 bronze badges

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