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@zpao zpao released this 19 Oct 22:14


  • Memory usage improvements - reduced allocations in core which will help with GC pauses
  • Performance improvements - in addition to speeding things up, we made some tweaks to stay out of slow path code in V8 and Nitro.
  • Standardized prop -> DOM attribute process. This previously resulting in additional type checking and overhead as well as confusing cases for users. Now we will always convert your value to a string before inserting it into the DOM.
  • Support for Selection events.
  • Support for Composition events.
  • Support for additional DOM properties (charSet, content, form, httpEquiv, rowSpan, autoCapitalize).
  • Support for additional SVG properties (rx, ry).
  • Support for using getInitialState and getDefaultProps in mixins.
  • Support mounting into iframes.
  • Bug fixes for controlled form components.
  • Bug fixes for SVG element creation.
  • Added React.version.
  • Added React.isValidClass - Used to determine if a value is a valid component constructor.
  • Removed React.autoBind - This was deprecated in v0.4 and now properly removed.
  • Renamed React.unmountAndReleaseReactRootNode to React.unmountComponentAtNode.
  • Began laying down work for refined performance analysis.
  • Better support for server-side rendering - react-page has helped improve the stability for server-side rendering.
  • Made it possible to use React in environments enforcing a strict Content Security Policy. This also makes it possible to use React to build Chrome extensions.

React with Addons (New!)

  • Introduced a separate build with several "addons" which we think can help improve the React experience. We plan to deprecate this in the long-term, instead shipping each as standalone pieces. Read more in the docs.


  • No longer transform class to className as part of the transform! This is a breaking change - if you were using class, you must change this to className or your components will be visually broken.
  • Added warnings to the in-browser transformer to make it clear it is not intended for production use.
  • Improved compatibility for Windows
  • Improved support for maintaining line numbers when transforming.