Get first key speed test

first-key.js

import each from 'lodash/each';

const getFirstKeyUsingEach = (obj) => {
  let firstKey = undefined;
  each(obj, (value, key) => {
    firstKey = key;
    return false; // Exit loop
  });
  return firstKey;
};

const getFirstKeyUsingObjectKeys = (obj) => {
  return Object.keys(obj)[0];
};

const KEYS = 100;
const obj = {};
for (let i = 0; i < KEYS; i++) {
  obj[i] = { foo: 'bar' };
}

const ITERATIONS = 100000;

it('first using Object.keys', () => {
  for (let i = 0; i < ITERATIONS; i++) {
    const key = getFirstKeyUsingObjectKeys(obj);
    // console.log({ key })
  }
});

it('first using each', () => {
  for (let i = 0; i < ITERATIONS; i++) {
    const key = getFirstKeyUsingEach(obj);
    // console.log({ key })
  }
});

// Results:
// first using Object.keys: 276, 265, 292 ms (FASTER)
// first using each: 299, 288, 302 ms