• Start Screen
  • Timer
  • Lap History

Difficulty: Easy

Code Breakdown:

  1. 7% HTML
  2. 11% CSS
  3. 82% JavaScript


Chrono is a simple chronometer with lap counter, built to highlight various aspects of the Firefox OS development process. Read the full developer walkthrough

Web API Usage

  • appcache

    Chrono does not require a network connection to run.

  • Open Web Apps

    Uses the Open Web Apps installation API to allow installation on the device independently on Marketplace.

Custom Elements

Third-party Libraries

  • volo.js

    Uses a volo.js script to optimize app before release, i.e. by auto-generating an appcache manifest.

  • jQuery

    Uses jQuery to simplify common tasks such as DOM manipulation.

  • RequireJS

    Uses RequireJS to split JavaScript code into more easily maintainable modules.