Web App

Approach

• Write only HTML5, CSS and Javascript.
• Write fast, memory-efficient, first-class Javascript.
• Lint your code frequently.
• Offline use localstorage (and JSON for non-string objects) to cache recent content. Or Lawnchair works on more platforms?
• Use mobile web best practices and Mobile-first design.
• xui or zepto are noticeably faster than jQuery + Underscore + Backbone. Bootstrap is also too heavy for mobiles.
• What about using AngularJS?
• Try out Appery and Intel XDK.
• Try Six as well. And Ratchet. Also moobile.
• See Component package manager & watch their screencasts.

Targets

• Desktop browsers as
  • a website
  • a Facebook canvas (or page tab) (that awkwardly is always requested as a POST)
• iOS 4.3+, Android, BlackBerry 7 & Windows Phone/RT tablet & phone browsers (with a manifest to ensure optimal caching)
• PhoneGap WebView
• Remote debug console for mobile testing
• http://caniuse.com/#feat=json