perfnow.js

About

perfnow.js is a micro-library written in both CoffeeScript and JavaScript.

Safely use microsecond precision timing using this 0.1 kb performance.now polyfill with Date fallback.

This minimal utility is compatible with all browsers as well as the more restricted web worker environment.

Examples

JavaScript

var t0 = performance.now();
doSomething();
var t1 = performance.now();
console.log("Call to doSomething took " + (t1 - t0) + " milliseconds.")

CoffeeScript

t0 = performance.now()
doSomething()
t1 = performance.now()
console.log "Call to doSomething took " + (t1 - t0) + " milliseconds."

Why?

Unlike other timing data available to JavaScript (for example Date.now), the timestamps returned by Performance.now() are not limited to one-millisecond resolution. Instead, they represent times as floating-point numbers with up to microsecond precision.

Also unlike Date.now, the values returned by Performance.now() always increase at a constant rate, independent of the system clock which might be adjusted manually or skewed by software such as the Network Time Protocol.

When?

There are a many situations where you should use this high resolution timer instead of a basic timestamp:

• benchmarking
• calculating framerate with precision
• cueing actions or audio to occur at specific points in an animation or other time-based sequence
• game or animation runloop code

Tested Environments

• Mac OS X

  • Google Chrome
  • Safari
  • Firefox
  • Opera

• Windows

  • Google Chrome
  • Safari
  • Firefox
  • Opera
  • Internet Explorer

Install Choices

• bower install perfnow
• download the zip

Tasks

All tasks can be run by simply running gulp or with the npm test command, or individually:

• gulp lint will lint source code for syntax errors and anti-patterns.
• gulp gpa will analyze source code against complexity thresholds.
• gulp test will run the jasmine unit tests against the source code.
• gulp test-coffee will run the jasmine unit tests against the CoffeeScript source code.
• gulp test-min will run the jasmine unit tests against the minified code.

License

(The MIT License)

Copyright (c) 2014 Daniel Lamb [email protected]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.