human-v-machine.js

#!/usr/bin/env node

// Results from MacBook (Retina, 12-inch, Early 2016), 1.3 GHz Intel Core m7, macOS 10.12.3, Node 7.6.0

// let a = { z: 1 }
// human-friendly x 85,821,153 ops/sec ±1.81% (87 runs sampled)
// machine-friendly x 92,613,579 ops/sec ±1.89% (85 runs sampled)
// Fastest is machine-friendly

// let a = undefined
// human-friendly x 93,950,465 ops/sec ±2.19% (85 runs sampled)
// machine-friendly x 93,779,232 ops/sec ±2.03% (85 runs sampled)
// Fastest is human-friendly,machine-friendly

const Benchmark = require('benchmark')
const suite = new Benchmark.Suite

let a = undefined

suite 
  .add('human-friendly',   function () { if (a) true })
  .add('machine-friendly', function () { if (a !== undefined) true })
  .on('complete', function () { console.log('Fastest is ' + this.filter('fastest').map('name')) })
  .on('cycle', function(event) { console.log(String(event.target)) })
  .run()

# MacBook Pro (Retina, 15-inch, Mid 2015),  2.2 GHz Intel Core i7, macOS 10.10.5

human-friendly x 78,400,466 ops/sec ±1.65% (82 runs sampled)
machine-friendly x 82,932,839 ops/sec ±1.32% (86 runs sampled)
Fastest is machine-friendly