lap

JavaScript performance testing library for the browser or server

API

Methods

• lap.time(laps, racers)
• lap.speed(laps, racers)
• lap.timestamp()

Parameters

• laps refers to number of laps to run (positive integer)
• racers refers to function(s) to race (array or single function)

Usage tips

• Use JavaScript exponential notation like 1e3 (rather than 1000) for expressing large numbers
• Accurate results require many laps. The ideal amount depends on how complex the racers are:
  • Infinity speeds and 0 times both indicate inadequate laps
  • Results taking too long indicates excessive laps. Use less laps or use the .async syntax

lap.time(laps, racers)

• Time how long it takes each racer to run the given number of laps
• @return array of times measured in milliseconds

.time example

lap.time(1e5, [
  function() { document.getElementById('example') },
  function() { document.querySelector('#example') },
  function() { document.querySelectorAll('#example')[0] }
]) // => [40.000000000873115, 44.99999999825377, 116.00000000180444]

lap.speed(laps, racers)

• Estimate each racer's average speed over a course of laps
• @return array of speeds measured in operations per second

.speed example

lap.speed(1e5, [
  function() { document.getElementById('example') },
  function() { document.querySelector('#example') },
  function() { document.querySelectorAll('#example')[0] }
]) // => [2500000.0004001777, 2222222.2219491494, 884955.7522315352]

lap.timestamp()

• Get a hi-resolution timestamp
• @return number measured in milliseconds

.timestamp example

lap.timestamp() // => 1610.000000000582

.async

• Methods are callable .async with the same arguments plus a (err, result) callback
• @return undefined

.async syntax

• lap.time.async(laps, racers, callback)
• lap.speed.async(laps, racers, callback)
• lap.timestamp.async(callback)

.async example

lap.time.async(1e5, function() {
  [].concat([0, 1, 2, 3])
}, function(err, result) {
  err || console.log(result[0] + ' ms')
}) // => undefined

.sync

.sync methods are included for expressiveness but these are just aliases. lap.time === lap.time.sync etc.

.sync example

lap.time.sync(1e5, [
  function() { document.getElementById('example') },
  function() { document.querySelector('#example') },
  function() { document.querySelectorAll('#example')[0] }
]) // => [40.000000000873115, 45.99999999481952, 115.00000000523869]

Compatibility

Works...everywhere! Tested in node, Chrome, FF, Opera, IE8

Contribute

$ npm start
$ npm test