Find all objects with matching Ids javascript

Question

I'm trying to get all objects with matching id's from my students array and get other property values from them...

For instance my array looks like this:

const students = [
    {id: 1, name: 'Cal', location: 'McHale' },
    {id: 2, name: 'Courtney', location: 'Sydney Hall' }, 
    {id: 1, name: 'Cal', location: 'Syndey hall' }
]

So my expected output would grab all instances of id: 1.

{id: 1, name: 'Cal', location: 'McHale' },
{id: 1, name: 'Cal', location: 'Syndey hall' }

I'll eventually want to remove duplicate names and display in a list like so... (But that's down the line. For now I just want to grab matching objects).

Id: 1    Name: Cal    Location: McHale
                                Syndey Hall

I've tried:

const result = _.find(students, {student_id: studentId});

But that doesn't seem to work, it just returns one of the objects with that id..

{id: 1, name: 'Cal', location: 'McHale' },

How can I make this work?

lodash.com/docs#filter - that said, given that it's an array you're filtering, not an object, you don't even need Lodash in this case. You can just use the built in Array.prototype.filter() function. — Joe Clay
– Joe Clay, Commented Jun 16, 2016 at 15:53
@JoeClay Huh, lodash filter seems easier. Is there a benefit to using . Array.prototype.filter() students.filter(x => x.student_id === studentId); ? — Modelesq
– Modelesq, Commented Jun 16, 2016 at 16:01
@Modelesq the built in one is probably faster because the lowdash one is doing a lot more stuff: github.com/lodash/lodash/blob/4.13.1/lodash.js#L8458 — JustGage
– JustGage, Commented Jun 16, 2016 at 16:29
Yep, @JustGage is right - in general I'd favor built-in methods over Lodash's where possible, as they tend to be implemented in native code rather than JavaScript, which usually ends up being faster. That said, unless this is taking place in a really performance-critical part of your code, it probably won't make a significant difference! — Joe Clay
– Joe Clay, Commented Jun 17, 2016 at 8:15

miken32 · Accepted Answer · 2025-02-08 19:49:13Z

32

I would look into the filter function. It's build into JavaScript.

Here's an example of how it works. All you need to do is find a way to make a function that will tell if it has the proper id.

function isBigEnough(value) {
  return value >= 10;
}
var filtered = [12, 5, 8, 130, 44].filter(isBigEnough);
// filtered is [12, 130, 44]

Source

edited Feb 8 at 19:49

miken32

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answered Jun 16, 2016 at 15:55

JustGage

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Comments

Gabriele Petrioli · Accepted Answer · 2016-06-16 16:00:54Z

9

If you see the documentation for _.find it states

Iterates over elements of collection, returning the first element predicate returns truthy for.

You should use the _.filter method for what you want

Iterates over elements of collection, returning an array of all elements predicate returns truthy for.

Something like

const result = _.filter(students, {student_id: studentId});

answered Jun 16, 2016 at 16:00

Gabriele Petrioli

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1 Comment

Modelesq Over a year ago

yeah i missed the "returning the first element part". haven't had my morning coffee thank you!

rahul · Accepted Answer · 2021-04-12 14:06:10Z

3

const result = students.filter(e => e.id === 1);

answered Apr 12, 2021 at 14:06

rahul

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Comments

Kz_3 · Accepted Answer · 2022-11-04 12:14:23Z

1

Find will always return the first matching element, regardless of how many other elements may match your condition.

If you want to extract all matching elements, you will need to use the .filter method.

The implementation is the same, but the result varies from an object (.find()) to an array (.filter())

answered Nov 4, 2022 at 12:14

Kz_3

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