Benchmark para https://pt.stackoverflow.com/q/432376/3635

README.md

• Para executar instale o Node.js

• Crie um projeto/pasta e instale o Benchmark.js:

  mkdir exemplo1
  cd exemplo1
  npm i --save benchmark
  

• Execute o comando node index.js

Deve obter algo como:

Math x 952,800,308 ops/sec ±0.21% (96 runs sampled)
while x 10,586,158 ops/sec ±0.96% (86 runs sampled)
padEnd x 11,894,867 ops/sec ±2.97% (88 runs sampled)
substring x 26,682,987 ops/sec ±1.95% (87 runs sampled)
Fastest is Math

index.js

var Benchmark = require('benchmark');

var suite = new Benchmark.Suite;

// add tests
suite

.add('Math', function() {
    var numero = 18;
    
    numero * Math.pow(10, 8 - Math.log(numero) * Math.LOG10E + 1 | 0);
})

.add('while', function() {
    var number = 18;
    var entry = number.toString();

    while (entry.length < 9) { entry += '0'; }
})

.add('padEnd', function() {
    var number = 18;

    number.toString().padEnd(9, '0');
})

.add('substring', function() {
    var number = 18;

    (number.toString() + '000000000').substring(0, 8);
})

// add listeners
.on('cycle', function(event) {
    console.log(String(event.target));
})
.on('complete', function() {
    console.log('Fastest is ' + this.filter('fastest').map('name'));
})

// run async
.run({ 'async': true });