- Added extensive cross‑browser event normalization and new support for SVG tags, attributes, and events (e.g., .currentTarget, .key polyfill, clipboardData, onMouseOver/Out, onLoad/onError).
- Introduced breaking API changes: lifecycle methods no longer receive the root node, removed deprecated React.unmountAndReleaseReactRootNode, .getValue() eliminated, renderComponentToString now synchronous, and default prop handling updated.
- Fixed numerous bugs and memory leaks, improved stack traces, added React.addons.TestUtils for unit testing, updated JSX whitespace handling with an automated codemod, and performed general performance optimizations.
Community impact
Community ratings: 0 Useful, 0 Noise, 0 Risky, 0 Broke, 0 Try.