An example of how to benchmark js code. In this example we compare 3 ways to remove elements from an array.

benchmark.js

var Benchmark = require('benchmark');
var suite = new Benchmark.Suite;
// add tests
suite.add('shift', function() {
        let arr = [1,2,3,4,5,6,7,8,9,0]
        for (let i in arr) {
            arr.shift()
        }
    })
    .add('slice', function() {
        let arr = [1,2,3,4,5,6,7,8,9,0]
        for (let i in arr) {
            arr.slice(1)
        }
    })
    .add('pop', function() {
        let arr = [1,2,3,4,5,6,7,8,9,0]
        for (let i in arr) {
            arr.pop()
        }
    })
    // 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': true });