Microsoft open sources Windows Library for JavaScript
Potentially helping developers more quickly build cross-platform applications, Microsoft is releasing as open source its WinJS JavaScript library for building Windows-styled controls. — Now that the library is open source …
Context & Ripple Effects
The move lands at Microsoft's Build developer conference, one day after the company unveiled Windows Phone 8.1 there, and sits inside an unusually busy open-sourcing day: alongside WinJS, Microsoft confirmed it is working with mobile-dev tool partner Xamarin on opening up .NET technologies and is releasing more of its .NET stack, including the placeholder
The story traveled unusually far for a library announcement — ZDNet, ReadWrite, InfoWorld, BetaNews all picked it up, and even GitHub hosted the news — reflecting how surprising it was to see the company behind Windows hand its signature UI toolkit to the community. Azure announcements at the same conference, from new load management to a raised 99.95% database uptime commitment, frame this as part of a broader developer-outreach push rather than an isolated gesture.
First-order effects
- Developers building Windows-styled controls can now take WinJS outside the Windows ecosystem entirely — fork it, contribute to it, and use it in apps targeting other platforms — which directly serves Microsoft's stated goal of faster cross-platform development.
- The WinJS project's roadmap shifts from internal-only to community-shaped: external contributors can propose changes to the very controls that define the Windows look.
Second-order effects
- Rival platform owners face rising developer expectations that core UI toolkits be inspectable and contributable, since Microsoft's own .NET open-sourcing with Xamarin reinforces the same message at the language and runtime level.
- Cross-platform tool vendors gain a new building block: a Microsoft-maintained, openly licensed control library lowers the cost of bringing Windows-styled interfaces into frameworks aimed at iOS and Android developers.
Third-order effects
- If the pattern holds, the boundary of what Microsoft treats as strategic secrecy keeps moving outward — from applications to libraries to languages — pushing the company's competitive moat toward services and cloud rather than proprietary developer tooling.
- A Windows UI standard maintained on public infrastructure could decouple the 'Windows experience' from Windows itself, weakening the historical lock between Microsoft's design identity and its operating system sales.
The trend: Microsoft is trading control of individual components like WinJS for reach, opening pieces of its once-closed developer stack so its platforms compete on ubiquity rather than exclusivity.