WebDev:FrontendCodeStandards

Browser Requirements

Support Levels

• A grade:
  • Roughly 90% or more of functionality and design is supported and functional
  • Variations between browsers is acceptable
  • 'Advanced' browsers can receive a higher fidelity experience with other browsers receiving a lower fidelity
• B grade:
  • Larger rendering issues allowed
  • Core functionality and content should still be accessible
  • Fallback to basic html from dhtml/ajax where necessary

If it's not on the chart, we don't support it.

Mobile Devices

	Support Level
Mobile IE	A-Grade
Fennec	A-Grade
Opera Mobile	A-Grade

Internal Tools

	Linux	Win XP	Vista	OS 10.5	OS 10.6
Fx 4.0	A-Grade	A-Grade	A-Grade	A-Grade	A-Grade
Fx 3.6	A-Grade	A-Grade	A-Grade	A-Grade	A-Grade
Fx 3.5	B-Grade	B-Grade	B-Grade	B-Grade	B-Grade

Minimum Browser Support

Support of other browsers is left to each product team.

	Linux	Win7	Win XP	Vista	OS 10.5	OS 10.6
IE 8		A-Grade	A-Grade	A-Grade
IE 7			A-Grade	A-Grade
Fx 4	A-Grade	A-Grade	A-Grade	A-Grade	A-Grade	A-Grade
Fx 3.5/3.6	A-Grade	A-Grade	A-Grade	A-Grade	A-Grade	A-Grade
Safari 4		A-Grade	A-Grade	A-Grade	A-Grade	A-Grade
Opera 10	A-Grade	A-Grade	A-Grade	A-Grade	A-Grade	A-Grade
Chrome		A-Grade	A-Grade	A-Grade
Gecko based	B-Grade	B-Grade	B-Grade	B-Grade	B-Grade	B-Grade

Other Support

• New Sites/Projects: Progressive enhancement for advanced functionality
• Current Sites: make new functionality degrade, don't rewrite current code
• Need to work on accessibility! (ex: AMO Control Panel)

QA Requirements

QA should test and file bugs appropriately for the browser support chart that applies to each site.

Accessibility Requirements

• Add basic ARIA support where appropriate

Code Standards

• Layered semantic markup
  • Semantic class/id names and appropriate HTML tags for content
  • No inline CSS & JS unless absolutely necessary
  • Progressive enhancement (see bolded QA requirements)
• HTML:
  • HTML5 doctype. Safe to use for all browsers.
  • Pages should validate. Not a strict requirement. Some layouts can't be achieved without a few errors.
  • Use most meaningful tags for content
  • Images/bg images with text in them must have alternate textual representation (alt text or text positioned offscreen for screenreaders). Avoid these due to L10n difficulties anyway.
• CSS:
  • Separate stylesheets for other browsers (IE) are ok
    • If only 1 or 2 properties are changed, keeping them in the original stylesheet is ok
  • For new sites, look into YUI Fonts & Reset, this will reduce browser layout differences
  • Semantic classnames
  • Don't use position: absolute unless absolutely necessary
  • Use least amount of selectors possible to allow for overriding
  • Don't use !important (see above)
  • Specify font sizes in EMs or %
  • Clear floats with zoom:1 & content:after
  • Hide content for screen readers with position:absolute and position offscreen. Display:none hides content from screen readers.
  • Design layouts to stretch according to their contents (good for localization and good for font-resizing)
  • Avoid selectors that are native element names (i.e. don't style on "div" or "p") except when resetting.
  • Specify in comments the scope of generic sounding class names (what does .block mean and where is it applied? one page or multiple pages?)
    • Try avoiding generic class names altogether
• JS
  • Don't pollute the global namespace (put all functions into objects/closures)
  • Use Module pattern for singletons? (http://yuiblog.com/blog/2007/06/12/module-pattern/)
  • Use .prototype for objects
  • Use jQuery
    • Very fast & light
    • If you need another library, please concatenate & use as little as possible
  • Make JS reusable as best as possible.
  • var your variables
  • Use JSlint : http://www.jslint.com/

Performance Standards

Page requirements

• Min score of B on homepage and 1 other 'major' page
• ~400k max page size

Recommendations

• Follow Yahoo!'s 34 rules http://developer.yahoo.com/performance/rules.html
• Follow these best practices: http://developer.yahoo.net/blog/archives/2008/01/the_7_habits_fo.html
• Sprite images
• Concat and minify JS & CSS with
  • YUI Compressor (http://www.julienlecomte.net/blog/2007/08/13/)
  • or Minify (http://code.google.com/p/minify/)
• Max 3s load time for all pages (tracked via Gomez)
• Use ySlow to see where pages can be improved

(see Webtools:Scalability for an overview of tools/infrastructure)

Security Standards

WebAppSec/Secure_Coding_Guidelines

Video Standards

• Players, in order of degradation...
  • <video>, obviously the first choice
    • Supported by FF 3.5+, Safari 3+, Chrome
  • Quicktime
    • IE w/ quicktime installed, iPhone
  • Flash
    • Check out open source JW-FLV player
    • YouTube, DailyMotion, etc are also options
  • Download links
    • If all else fails, at least let the user download easily

• Formats
  • Webm - Firefox
  • OGG
  • MP4 / H.264 - everything else
  • Consider high vs. low vs. audio-only formats?

• Resources
  • Video For Everybody - excellent page detailing complete setup, from codecs to HTML
  • Open source flash player

• Hosting
  • Currently, file a bug with IT (mozilla.org:server ops) and host at videos.mozilla.org
  • https://intranet.mozilla.org/Uploading_Videos
  • Link to videos should use CDN (videos-cdn.mozilla.net)