Filter an Object based on values in array

Question

I encountered a small problem, that I can't figure out or find a solution to, on the internet, at least that I'm aware of. I want to filter an object in javascript, based on a undefined number of values in an array. I have an object like this:

categories = { "category1: {"_id": "1234"}, "category2: {"_id": "4567"}, ... };

I also have an array including values of IDs, like so:

catArray = ["1234", "4567", ... ]

Now I want to filter all categories out of the category-Object, matching the IDs from the array. I managed to filter the category for a single array-value, but not for all. It's working like this:

const categoriesFilter = categories.filter(cat => {
        return cat._id == catArray[0];
});

So far it is working. But now I want to match the categories from all possible ID-values from the array. I tried to do it with a for-loop, but it's not working out. Any idea? Thanks a lot in advance.

That shouldn’t be working, since you said categories was a plain object. Those don’t have filter. Is categories actually an array? — Ry-
– Ry- ♦, Commented Dec 1, 2018 at 14:56
It shouldn't be working another way: _id doesn't match the data either which has id. — Andy
– Andy, Commented Dec 1, 2018 at 15:04
Maybe i switched the category. I got it from some other code and it is working, i just put that object above as an example. And the ID was a mistake. It should be "_id" — ahmkay
– ahmkay, Commented Dec 1, 2018 at 15:21

Andy · Accepted Answer · 2018-12-01 15:49:59Z

1

Categories should be an array of objects, for example. Then you can use .filter():

let categories = [{ "id": "1234" }, { "id": "4567" }];
let catArray = ["1234", "45674"];

const categoriesFilter = categories.filter(cat => {
  return catArray.includes(cat.id);
});

console.log(categoriesFilter);

edited Dec 1, 2018 at 15:49

Andy

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answered Dec 1, 2018 at 15:00

Kresimir

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5 Comments

Andy Over a year ago

That isn't a valid array.

Kresimir Over a year ago

It isn't, you're supposed to fill the ... with other elements.

Andy Over a year ago

No. You still have object keys in there. category1 for example.

Kresimir Over a year ago

You're right. Sorry, didn't pay attention. Edited the answer.

Andy Over a year ago

Just added a snippet to your answer.

Nenad Vracar · Accepted Answer · 2018-12-01 15:04:12Z

0

You could first create one object with id as keys and then use it as lookup table to create new object with filtered properties by array.

const cat = { category1: {"id": "1234"}, category2: {"id": "4567"}, category3: {"id": "123"}};
const arr = ["1234", "4567" ]
const hash = Object.entries(cat)
  .reduce((r, [k, v]) => Object.assign(r, {[v.id]: {[k]: v}}), {})

const result = arr.reduce((r, id) => {
  if(hash[id]) Object.assign(r, hash[id])
  return r;
}, {})

console.log(result)

answered Dec 1, 2018 at 15:04

Nenad Vracar

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Comments

James Jithin · Accepted Answer · 2018-12-01 15:24:36Z

0

You may do :

var categories = { "category1": {"id": "1234"}, "category2": {"id": "4567"}, "category4": {"id": "45678"}}; var catArray = ["1234", "4567"]; var categoriesFilter = Object.entries(categories).filter(([catKey,catValue]) => { return catArray.includes(catValue.id); });

answered Dec 1, 2018 at 15:24

James Jithin

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1 Comment

ahmkay Over a year ago

that worked half way. I can iterate now trough the IDs from the array. But all the other keys and values from the categories objects got lost.

Adam Orłowski · Accepted Answer · 2018-12-01 15:35:51Z

0

const categories = { category1: {"id": "1234"}, category2: {"id": "4567"}, category3: {"id": "123"}};
const catArray = ["1234", "4567" ]
const checkIfArrIncludes = (id) => catArray.includes(id);
const matchedCats = Object.values(categories).filter(cat => (checkIfArrIncludes(cat.id) ? cat : 0));

answered Dec 1, 2018 at 15:35

Adam Orłowski

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