use-ref-from v0.1.0

use-ref-from

React.useRef with an immediate setter and read-only value.

Background

Aids useCallback and useMemo for better memoization, reduce wasted render, and properly signal render loop.

By using useRefFrom, React component developers can make sure their custom hooks are properly memoized.

How to use

Following examples shows how useRefFrom help decoupling mutation for callbacks.

Without using useRefFrom

Return function from useCallback could change on every render.

const MyComponent = ({ message }: { message: string }) => {
  // `handleClick` changes on every update to `message`.
  const handleClick = useCallback(() => {
    alert(message);
  }, [message]);

  return <button onClick={handleClick}>Click me</button>;
};

Decoupling mutation without useRefFrom

Decoupling message from useCallback by useRef.

const MyComponent = ({ message }: { message: string }) => {
  const messageRef = useRef<string>();

  messageRef.current = message;

  // `handleClick` stay intact regardless of `message`.
  const handleClick = useCallback(() => {
    // `messageRef.current` is `string | null`, unsafe casting is required.
    alert(messageRef.current as string);
  }, [messageRef]);

  return <button onClick={handleClick}>Click me</button>;
};

Decoupling value with useRefFrom

Decoupling value from useCallback by useRefFrom. It also helps typing and read-only.

const MyComponent = ({ message }: { message: string }) => {
  const messageRef = useRefFrom<string>(message);

  // `handleClick` stay intact regardless of `message`.
  const handleClick = useCallback(() => {
    // `messageRef.current` is `readonly string`.
    alert(messageRef.current);

    // ❌ `messageRef.current` is read-only. The following line will fail at compile-time.
    messageRef.current = 'Hello, World!'.
  }, [messageRef]);

  return <button onClick={handleClick}>Click me</button>;
};

API

function useRefFrom<T>(value: T): RefObject<T> & { get current(): T };

Behaviors

Ref object cannot be set

The RefObject<T> returned by useRefFrom() will be read-only and cannot be set. This is by design.

Contributions

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