keyed-object-array.js

// Let’s say we received an array of users in the form {id:..., name:..., age:... }.

// Create a function groupById(arr) that creates an object from it, with id as the key, and array items as values.

// For example:

// let users = [
//   {id: 'john', name: "John Smith", age: 20},
//   {id: 'ann', name: "Ann Smith", age: 24},
//   {id: 'pete', name: "Pete Peterson", age: 31},
// ];

// let usersById = groupById(users);

// /*
// // after the call we should have:

// usersById = {
//   john: {id: 'john', name: "John Smith", age: 20},
//   ann: {id: 'ann', name: "Ann Smith", age: 24},
//   pete: {id: 'pete', name: "Pete Peterson", age: 31},
// }
// */
// Such function is really handy when working with server data.

// In this task we assume that id is unique. There may be no two array items with the same id.

// Please use array .reduce method in the solution.

let users = [
  {id: 'john', name: "John Smith", age: 20},
  {id: 'ann', name: "Ann Smith", age: 24},
  {id: 'pete', name: "Pete Peterson", age: 31},
];

function groupById(array) {
    return array.reduce((obj, value) => {
        obj[value.id] = value;
        return obj;
    }, {})
}

let usersById = groupById(users);

console.log(usersById);