How to convert an array to an object

Short answer

Object.fromEntries() builds an object from an array of key-value pairs:

const pairs = [['name', 'Anna'], ['age', 30]];
 
console.log(Object.fromEntries(pairs));

Output:

{
  "name": "Anna",
  "age": 30
}

An index by id

To quickly find objects by id, make an object where the key is the id:

const users = [
  { id: 7, name: 'Anna' },
  { id: 9, name: 'Oleg' },
];
const byId = Object.fromEntries(users.map((user) => [user.id, user]));
 
console.log(byId[9].name);

Output:

Oleg

Two arrays: keys and values

Pair the elements of two arrays by their index:

const keys = ['red', 'green', 'blue'];
const values = ['#f00', '#0f0', '#00f'];
const colors = Object.fromEntries(keys.map((key, i) => [key, values[i]]));
 
console.log(JSON.stringify(colors));

Output:

{"red":"#f00","green":"#0f0","blue":"#00f"}

Common mistake

The spread operator turns an array into an object with numeric keys, which is rarely what you need:

console.log(JSON.stringify({ ...['a', 'b'] }));

Output:

{"0":"a","1":"b"}

Thanks for reading!

Short answer

An index by id

Two arrays: keys and values

Common mistake

Functions used in this recipe

Thanks for reading!