BN vs number benchmark

bn_vs_number.js

const Benchmark = require('benchmark')
const BN = require('bn.js')

const suite = new Benchmark.Suite

let num_a, num_b
let bn_a, bn_b

const randInt = () => Math.floor(Math.random() * 2**24)

const genNewInputs = () => {
  num_a = randInt()
  num_b = randInt()
  bn_a = new BN(num_a)
  bn_b = new BN(num_b)
}

const options = {
  onStart: genNewInputs,
  onCycle: genNewInputs,
}

suite
  .add('BN#add', () => bn_a.add(bn_b), options)
  .add('BN#sub', () => bn_a.sub(bn_b), options)
  .add('BN#div', () => bn_a.div(bn_b), options)
  .add('BN#mul', () => bn_a.mul(bn_b), options)
  .add('number#add', () => num_a + num_b, options)
  .add('number#sub', () => num_a - num_b, options)
  .add('number#div', () => Math.floor(num_a / num_b), options)
  .add('number#mul', () => num_a * num_b, options)
  .on('cycle', (evt) => console.log(String(evt.target)))
  .run({async: true})

/*
$ node --version
v10.15.1
$ node bn_vs_number.js
BN#add x 42,634,555 ops/sec ±1.14% (91 runs sampled)
BN#sub x 21,596,668 ops/sec ±2.56% (84 runs sampled)
BN#div x 20,553,396 ops/sec ±8.56% (62 runs sampled)
BN#mul x 60,923,258 ops/sec ±1.62% (90 runs sampled)
number#add x 166,492,969 ops/sec ±0.21% (92 runs sampled)
number#sub x 166,453,714 ops/sec ±0.47% (93 runs sampled)
number#div x 167,928,989 ops/sec ±0.42% (89 runs sampled)
number#mul x 171,253,179 ops/sec ±0.39% (90 runs sampled)
*/