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gemini-nexus/.agent/skills/vercel-react-best-practices/rules/rerender-use-ref-transient-values.md
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AngeloooooandDraculabo 8ed4593f73 Refactor Gemini model display: filter old versions, group low/high pкo, and improve naming (#114)
* Refactor Gemini model display: filter old versions, group low/high pro, and improve naming

* Fix potential negative minutes and refine Gemini 3 Pro grouping logic based on PR feedback

* The account change process has been sped up

* Address PR review: enhance error message and parameterize polling interval in process handler

* Address PR review: fix potential race condition in database backup logic

* fix: prevent renderer white screen and harden sentry gating

* feat:  localize model labels

* chore: enable hoisted node-linker

* chore: ignore .agent/.claude/.codex in prettier

---------

Co-authored-by: Draculabo <[email protected]>
2026-02-19 19:37:30 +08:00

1.7 KiB

title, impact, impactDescription, tags
title impact impactDescription tags
Use useRef for Transient Values MEDIUM avoids unnecessary re-renders on frequent updates rerender, useref, state, performance

Use useRef for Transient Values

When a value changes frequently and you don't want a re-render on every update (e.g., mouse trackers, intervals, transient flags), store it in useRef instead of useState. Keep component state for UI; use refs for temporary DOM-adjacent values. Updating a ref does not trigger a re-render.

Incorrect (renders every update):

function Tracker() {
  const [lastX, setLastX] = useState(0);

  useEffect(() => {
    const onMove = (e: MouseEvent) => setLastX(e.clientX);
    window.addEventListener('mousemove', onMove);
    return () => window.removeEventListener('mousemove', onMove);
  }, []);

  return (
    <div
      style={{
        position: 'fixed',
        top: 0,
        left: lastX,
        width: 8,
        height: 8,
        background: 'black',
      }}
    />
  );
}

Correct (no re-render for tracking):

function Tracker() {
  const lastXRef = useRef(0);
  const dotRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    const onMove = (e: MouseEvent) => {
      lastXRef.current = e.clientX;
      const node = dotRef.current;
      if (node) {
        node.style.transform = `translateX(${e.clientX}px)`;
      }
    };
    window.addEventListener('mousemove', onMove);
    return () => window.removeEventListener('mousemove', onMove);
  }, []);

  return (
    <div
      ref={dotRef}
      style={{
        position: 'fixed',
        top: 0,
        left: 0,
        width: 8,
        height: 8,
        background: 'black',
        transform: 'translateX(0px)',
      }}
    />
  );
}