7 things I learned from React sourcecode. Website: http://facebook.github.io/react

7-things-react.md

It's all about Components.

• Components can be created at runtime via createClass
• Stringified and parsed
• Existing DOM can be parsed via a "mount" algorithm.

DOM changes

• React is event based and not "frame" based. It's not using a timer. DOM changes are cached until all events are done and flushed at once.
• setState triggers DOM changes explicitly

Dependency injection

• Objects have injection property that holds setters for injecting dependencies
• DOM is abstracted. Modules like performanceNow are using Date.now() fallback in case DOM (or performance.now) is not available

Transaction

Holds a task. A task that can be cached, pooled, queued and allows other transactions to wait until previous tasks are resolved. var transaction = perform(function() { doSth(); }); release(transaction);

WebWorker

There are hints that they tried but failed using WebWorkers (internally called "ReactWorker") so far. Apparently preventDefault was one of the problems they ran in to while running a Component within a separate thread. Maybe a future use case could be performing "Transactions" within a worker.

General

• License: http://www.apache.org/licenses/LICENSE-2.0
• Commonjs by default / supports amd too
• Coding guidelines completely reasonable. Nothing fancy.
• Compiler hinting, logging and assertions (including best practice suggestions) all over the place
  • if (__DEV__),
  • if ("production" !== "development") {
  • invariant(true, 'Must be true');
• Some functions are "measured" at runtime. E.g. Time spend to mount a Component. Results are reported somehow. I guess mostely via console.
• Function naming known from Cocoa
  • componentWillMount
  • componentDidMount
  • release

So much useful code

• object pooling
• services (performance.now())