Avoid using reduce in JavaScript

Question

Avoid using reduce in JavaScript

I'm attempting to extract specific values from an object with the status of 'xyz'

user.friends =
CoreMongooseArray [
{ _id: 5b11824350c0011afe9ca310,
user:
 { profile: [Object],
   _id: 5b11805a50c0011afe9ca2fe,
   username: 'user1' },
status: 'abc' },
{ _id: 5b191033d240ab4a10ffb54f,
user:
 { profile: [Object],
   _id: 5b0ec81f958f5b4919b83c40,
   username: 'user2' },
status: 'xyz' } ]

I am utilizing

user.friends.reduce((a, t) => a + (t.type === 'xyz' ? 0 : 1), 0);

However, instead of only returning the object with the username user2 like I expect, it is only returning 1. Why is this happening?

javascript

Answer 1

Answer №1

Why does it only return the number 1 instead of the object with the username user2?

It returns 1 because that's the last value returned by your callback function when using the reduce method.

If you are looking to find a specific object in an array based on a certain criterion, using reduce may not be the best approach. Instead, consider using the find method:

const oneXYZFriend = user.friends.find(e => e.status === 'xyz');

(Note that I changed the comparison from e.type === 'xyz' to e.status === 'xyz' assuming your objects have a status property, not a type property.)

If you need to find multiple objects in an array that meet a given criteria, you should use filter:

const xyzFriends = user.friends.filter(e => e.status === 'xyz');

Answer 2

Why does it only return the number 1 instead of the object with the username user2?

It returns 1 because that's the last value returned by your callback function when using the reduce method.

If you are looking to find a specific object in an array based on a certain criterion, using reduce may not be the best approach. Instead, consider using the find method:

const oneXYZFriend = user.friends.find(e => e.status === 'xyz');

(Note that I changed the comparison from e.type === 'xyz' to e.status === 'xyz' assuming your objects have a status property, not a type property.)

If you need to find multiple objects in an array that meet a given criteria, you should use filter:

const xyzFriends = user.friends.filter(e => e.status === 'xyz');

Avoid using reduce in JavaScript

Answer №1

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