React Core

Breaking Changes

• getDefaultProps() is now called once per class and shared across all instances
• MyComponent() now returns a descriptor, not an instance
• React.isValidComponent and React.PropTypes.component validate descriptors, not component instances
• Custom propType validators should return an Error instead of logging directly

New Features

• Rendering to null
• Keyboard events include normalized e.key and e.getModifierState() properties
• New normalized onBeforeInput event
• React.Children.count has been added as a helper for counting the number of children

Bug Fixes

• Re-renders are batched in more cases
• Events: e.view properly normalized
• Added Support for more HTML attributes (coords, crossOrigin, download, hrefLang, mediaGroup, muted, scrolling, shape, srcSet, start, useMap)
• Improved SVG support
  • Changing className on a mounted SVG component now works correctly
  • Added support for elements mask and tspan
  • Added support for attributes dx, dy, fillOpacity, fontFamily, fontSize, markerEnd, markerMid, markerStart, opacity, patternContentUnits, patternUnits, preserveAspectRatio, strokeDasharray, strokeOpacity
• CSS property names with vendor prefixes (Webkit, ms, Moz, O) are now handled properly
• Duplicate keys no longer cause a hard error; now a warning is logged (and only one of the children with the same key is shown)
• img event listeners are now unbound properly, preventing the error "Two valid but unequal nodes with the same data-reactid"
• Added explicit warning when missing polyfills

React With Addons

• PureRenderMixin: a mixin which helps optimize "pure" components
• Perf: a new set of tools to help with performance analysis
• Update: New $apply command to transform values
• TransitionGroup bug fixes with null elements, Android

React NPM Module

• Now includes the pre-built packages under dist/.
• envify is properly listed as a dependency instead of a peer dependency

JSX

• Added support for namespaces, eg <Components.Checkbox />
• JSXTransformer
  • Enable the same harmony features available in the command line with <script type="text/jsx;harmony=true">
  • Scripts are downloaded in parallel for more speed. They are still executed in order (as you would expect with normal script tags)
  • Fixed a bug preventing sourcemaps from working in Firefox

React Tools Module

• Improved readme with usage and API information
• Improved ES6 transforms available with --harmony option
• Added --source-map-inline option to the jsx executable
• New transformWithDetails API which gives access to the raw sourcemap data