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React Versions

React 19​

Links:

WDS: NEW React 19 Changes Are Amazing​

Source: https://www.youtube.com/watch?v=v07gXY6ESEo

  • React compiler is going to automatically apply useMemo, useCallback, and memo
  • it's going to find more instances when you should be using them than you normally would
  • Actions allow you to pass a function to DOM elements such as a form
    • instead of an onSubmit, you use an action
  • useOptimistic allows you to do optimistic updates (you click a like button and it shows that it is updated even though you haven't sent the request to the server yet)
  • adding "use client" and "use server".
  • Document Metadata can be added anywhere in the component and it'll be added to the head of the document
  • you won't need forwardRef anymore
  • you can use the use hook which can replace lazy

React 18​

  • Introduced concurrent rendering features (automatic batching by default)
  • New root API: ReactDOM.createRoot() for improved performance and concurrency
  • SSR streaming support with Suspense on the server
  • Added new hook: useId for generating stable unique IDs
  • Improved strict mode behavior and hydration mismatch handling

React 17​

  • No new developer-facing features; focused on a gradual upgrade path
  • New JSX transform: no need to import React in every file
  • Updated event delegation: listeners attach to the root instead of the document
  • Improved support for future async rendering migrations

React 16​

  • Complete rewrite of core architecture (Fiber) for better reconciliation
  • Introduced error boundaries via componentDidCatch
  • Added portals using ReactDOM.createPortal to render outside parent DOM hierarchy
  • Fragment syntax support: <>...</>
  • New Context API with React.createContext
  • Hooks introduced in React 16.8: useState, useEffect, useContext, etc.

React 15​

  • Legacy lifecycle methods (componentWillMount, componentWillReceiveProps, etc.)
  • Stateless functional components without hooks
  • React Addons separated into standalone packages (e.g., react-addons-css-transition-group)
  • Performance tool react-addons-perf for profiling
  • Official support dropped for IE8

Versioning note: 0.14 to 15​

After React 0.14, the next major release was React 15; there were no versions 1.x through 14.x.

React 0.14​

  • React and ReactDOM split into separate packages (react vs react-dom)
  • Stateless functional components became a first‑class citizen
  • Enabled custom renderers (React Native, etc.) via new Reconciler API
  • Removed two‑way data binding and mixin support for ES6 classes

React 0.13​

  • Introduced ES6 class component support alongside React.createClass
  • Stateless functional components simplified component definitions
  • Performance improvements in reconciliation algorithm
  • TransitionGroup and LinkedStateMixin provided as addons