benchmark_underscore.js

gistfile1.js

#! /usr/bin/env node

var Underscore = require('./underscore')

function randomizedArray(size, limit) {
  var result = []
  for (var i=0; i < size; i++) {
    var rnd = Math.floor(Math.random() * limit)
    result.push(rnd + '')
  }
  return result
}

function elapsedTime(fn) {
  var start = Date.now()
  var result = fn()
  var elapsed = Date.now() - start
  return [result, elapsed]
}

// Our implementation
function intersect(a, b) {
  var obj = {}
  for (var i=0; i < a.length; i++) {
    obj[ a[i] ] = true
  }
  var both = {}
  for (var i=0; i < b.length; i++) {
    if (obj[ b[i] ] != null)
      both[ b[i] ] = true
  }
  var result = []
  for (var k in both) {
    result.push(k)
  }
  return result
}

function timeIntersect() {
  var a = randomizedArray(20000, 100000)
  var b = randomizedArray(30000, 100000)
  
  var u = elapsedTime(function() { return Underscore.intersect(a, b) })
  var m = elapsedTime(function() { return intersect(a, b) })
    
  if (u[0].length != m[0].length) {
    console.log("* experiment failed: u[0].length=" + u[0].length + 
                "; m[0].length=" + m[0].length)
  } else {
    console.log("Underscore.intersect ms: " + u[1])
    console.log("My.intersect         ms: " + m[1])
    console.log("My.intersect is " + Math.floor(u[1] / m[1]) + " times faster" )
  }
}

timeIntersect()

/*
Underscore.intersect ms: 20835
My.intersect         ms: 14
My.intersect is 1488 times faster
*/