How to filter a JavaScript object in react-native

Question

I want to show a list of user uids and some information about them, except for the information of a specific user.

Here is an example of my JavaScript object, which I am storing in as a usersData state:

{
  "alkfklnj2340": {
    "uid": "alkfklnj2340",
    "username": "username1"
  },
  "235o2hifoiid": {
    "uid": "235o2hifoiid",
    "username": "username2"
  }
}

For example, I want to return a new object without alkfklnj2340, so:

{
  "235o2hifoiid": {
    "uid": "235o2hifoiid",
    "username": "username2"
  }
}

I have tred this so far, which doesn't quite output what is expected:

const filteredUsers = Object.keys(this.state.usersData).filter((key, i) =>
    this.state.usersData[key].uid != this.state.userUid
);

What are you expecting it to output and what value are you getting? What is userUid? — Spangle
– Spangle, Commented Nov 29, 2019 at 4:30

wrsx · Accepted Answer · 2019-11-29 04:43:22Z

1

You could use a for...in loop

let result = {};
for (const key in this.state.usersData) {
    if (key !== this.state.userUid) {
        result[key] = this.state.usersData[key];
    }
}

or a forEach loop:

let result = {};
Object.keys(this.state.usersData).forEach(key => {
  if (key !== this.state.userUid) {
    result[key] = this.state.usersData[key];
  }
});

edited Nov 29, 2019 at 4:43

answered Nov 29, 2019 at 4:32

wrsx

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Comments

Peeranut Chindanonda · Accepted Answer · 2019-11-29 04:38:04Z

0

You can use reduce to construct a new dictionary.

var filteredUsers = Object.keys(this.state.usersData).reduce((filteredUsers, key) => {
    if (this.state.usersData[key].uid != this.state.userUid) {
        filteredUsers[key] = this.state.usersData[key];
    }
    return filteredUsers;
}, {});

This will start from a new dictionary {} and keep setting key+value when the condition is met.

You can also do it like this:

var filteredUsers = Object.fromEntries(Object.entries(this.state.usersData).filter(([key,value]) => this.state.usersData[key].uid != this.state.userUid));

Object.entries() turns dictionary into an entry list. Object.fromEntries() turns an entry list back to a dictionary.

edited Nov 29, 2019 at 4:38

answered Nov 29, 2019 at 4:30

Peeranut Chindanonda

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