javascript: array to hash for search

array-to-hash-for-search.js

// array to hash for search
const users = [];
const products = [];

const elem = 10;

const keyBy = (arr, key) => arr.reduce((acc, el) => {
  //console.log('acc', acc);
  //console.log('acc[el]', el);
  //console.log('acc[el[key]]', el[key]);
  acc[el[key]] = el;
  return acc;
}, {});

for (let i = 0; i < elem; i++) {
  users.push({
    id: i,
    nombre: `nombre-${i}`
  });
}

for (let i = 0; i < elem; i++) {
  products.push({
    id: i,
    nombre: `nombre-producto-${i}`,
    user_id: Math.floor(Math.random() * elem)
  });
}

const keyedUsers = keyBy(users, 'id');

console.time();
const mezclados = products.map(x => ({
  ...x,
  //user: users.find(y => y.id === x.user_id)
  user: keyedUsers[x.user_id]
}));
console.timeEnd();
console.log('mezclados:', mezclados[0]);