Built-in React APIs

• createContext lets you define and provide context to the child components. Used with useContext.
• lazy lets you defer loading a component’s code until it’s rendered for the first time.
• memo lets your component skip re-renders with same props. Used with useMemo and useCallback.
• startTransition lets you mark a state update as non-urgent. Similar to useTransition.
• addTransitionType lets you specify the cause of a Transition. Used with startTransition and <ViewTransition>.
• act lets you wrap renders and interactions in tests to ensure updates have processed before making assertions.
• cache lets you cache the result of a data fetch or computation.
• cacheSignal lets you know when the cache() lifetime is over.
• captureOwnerStack reads the current Owner Stack in development and returns it as a string if available.

Resource APIs

Resources can be accessed by a component without having them as part of their state. For example, a component can read a message from a Promise or read styling information from a context.

You can pass these types of resources to use:

• A Promise to read its resolved value.
• A context to read its value.
• The value returned by browser to mark a component as browser-only during server rendering.

function MessageComponent({ messagePromise }) {
  const message = use(messagePromise);
  const theme = use(ThemeContext);
  use(browser());
  // ...
}