updating array in object properties using properties

Question

I have an object defined like this:

import React, { Component } from 'react';
import './App.css';

class App extends Component {

  constructor() {
    super();
    this.state = {
    lists: ["Dogs", "Cats"],
    items: {Dogs:[], Cats:[]}
    };
  }

  handleAddItem(item) {
    console.log(item);
  }

I have the variable

console.log(item);// output {Dogs:[{name: "lofi"}]}

I don't know how to verify which property is in the item (Dogs or Cats) so that I can update the object items{} to make it becоme in my example like this:

items{Dogs:[{name: "lofi"}], Cats:[]}

What do you mean with verify?

Gerardo BLANCO
– Gerardo BLANCO

2018-06-05 12:25:35 +00:00
Commented Jun 5, 2018 at 12:25 — Gerardo BLANCO
– Gerardo BLANCO, Commented Jun 5, 2018 at 12:25

Mihai Alexandru-Ionut · Accepted Answer · 2018-06-05 12:25:47Z

1

You can use Object.keys method.

items[Object.keys(item)[0]] = item[Object.keys(item)[0]]

Working solution

let state = {
   lists: ["Dogs", "Cats"],
   items: {Dogs:[], Cats:[]}
};

let item = { Dogs:[{name: "lofi"}] };
state.items[Object.keys(item)[0]] = item[Object.keys(item)[0]]
console.log(state.items);

answered Jun 5, 2018 at 12:25

Mihai Alexandru-Ionut

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1 Comment

E.Mohammed Over a year ago

I can't use '{ Dogs: [ {name: "lofi"} ] }' explicitly, I have to use the object 'item' and look for the same property in 'items' to update

Suren Srapyan · Accepted Answer · 2018-06-05 12:26:05Z

1

You can use Object.assign function on the state.items, which will add/update the given object with the properties given at the second parameter.

let state = {
   lists: ["Dogs", "Cats"],
   items: { Dogs:[], Cats:[] }
};

let item = { Dogs: [ {name: "lofi"} ] };

Object.assign(state.items, item);

console.log(state);

answered Jun 5, 2018 at 12:26

Suren Srapyan

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4 Comments

E.Mohammed Over a year ago

I can't use '{ Dogs: [ {name: "lofi"} ] }' explicitly, I have to use the object 'item' and look for the same property in 'items' to update.

Suren Srapyan Over a year ago

Will your item contain either Dogs or Cats?

E.Mohammed Over a year ago

yes, both Dogs or Cats or even other animals that I can add

Suren Srapyan Over a year ago

You don't need to know what is in the item, it just gets the properties from that and put them into the state.items

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