object-keys-assoc.js

import Benchmark from 'benchmark'

const suite = new Benchmark.Suite()
const obj = {
  a: 1,
  b: 2,
  c: 3,
}
const obj2 = {
  a: 1,
  b: 2,
  c: 3,
}
obj2.keys = Object.keys(obj2)
const assoc = [
  ["a", 1],
  ["b", 2],
  ["c", 3],
]

suite
  .add('a', () => {
    const o = {}
    const keys = Object.keys(obj)
    for (let i = 0; i < keys.length; i++) {
      o[keys[i]] = obj[keys[i]]
    }
  })
  .add('b', () => {
    const o = {}
    for (let i = 0; i < assoc.length; i++) {
      o[assoc[i][0]] = assoc[i][1]
    }
  })
  .add('c', () => {
    const o = {}
    for (let i = 0; i < obj2.keys.length; i++) {
      o[obj2.keys[i]] = obj2[obj2.keys[i]]
    }
  })
  .on('cycle', (event) => {
    console.log(String(event.target))
  })
  .on('complete', function () {
    console.log(`Fastest is ${this.filter('fastest').map('name')}`)
  })
  .run({ async: true })

result

a x 8,140,534 ops/sec ±2.78% (82 runs sampled)
b x 12,668,517 ops/sec ±1.82% (85 runs sampled)
c x 9,372,974 ops/sec ±3.00% (85 runs sampled)