`react-doctor/no-unthrottled-scroll-mutation`

Scroll handler drives animation every event

Category: Performance
Severity: warn
Source: oxlint-plugin-react-doctor
Framework: global
Enabled when: react
Default: Enabled

Validate the diagnostic

Confirm the reported code matches this rule before you edit it.

Confirm the reported code matches react-doctor/no-unthrottled-scroll-mutation. Compare it with the Before example and verify the same API, framework, and execution context. Treat it as a false positive only when one of those conditions differs.

Compare the code

The corrected pattern shows a focused way to address the diagnostic.

Reported pattern

import { useEffect } from "react";

const Hero = () => {
  useEffect(() => {
    const hero = document.querySelector(".hero");
    if (!hero) return;
    const onScroll = () => {
      hero.style.transform = `translateY(${window.scrollY}px)`;
    };
    window.addEventListener("scroll", onScroll);
    return () => window.removeEventListener("scroll", onScroll);
  }, []);
  return null;
};

Corrected pattern

import { useEffect } from "react";

const Hero = () => {
  useEffect(() => {
    const hero = document.querySelector(".hero");
    if (!hero) return;
    let timerId: number | undefined;
    const onScroll = () => {
      if (timerId) return;
      timerId = window.setTimeout(() => {
        hero.style.transform = `translateY(${window.scrollY}px)`;
        timerId = undefined;
      }, 100);
    };
    window.addEventListener("scroll", onScroll);
    return () => {
      window.clearTimeout(timerId);
      window.removeEventListener("scroll", onScroll);
    };
  }, []);
  return null;
};

How to fix

Use the corrected pattern as a reference. Preserve behavior that the rule does not require you to change.

Copyable fix prompt

Copy this self-contained prompt into your coding agent after you confirm the diagnostic.

Fix every confirmed react-doctor/no-unthrottled-scroll-mutation diagnostic in the current repository. Required change: - Use a scroll or view timeline, IntersectionObserver, or a real timer throttle so animation work does not run for every scroll event.

Reference transformation:Before:

import { useEffect } from "react";

const Hero = () => {
  useEffect(() => {
    const hero = document.querySelector(".hero");
    if (!hero) return;
    const onScroll = () => {
      hero.style.transform = `translateY(${window.scrollY}px)`;
    };
    window.addEventListener("scroll", onScroll);
    return () => window.removeEventListener("scroll", onScroll);
  }, []);
  return null;
};

After:

import { useEffect } from "react";

const Hero = () => {
  useEffect(() => {
    const hero = document.querySelector(".hero");
    if (!hero) return;
    let timerId: number | undefined;
    const onScroll = () => {
      if (timerId) return;
      timerId = window.setTimeout(() => {
        hero.style.transform = `translateY(${window.scrollY}px)`;
        timerId = undefined;
      }, 100);
    };
    window.addEventListener("scroll", onScroll);
    return () => {
      window.clearTimeout(timerId);
      window.removeEventListener("scroll", onScroll);
    };
  }, []);
  return null;
};

Constraints: - Confirm the reported code matches the Before pattern. - Make the smallest change that fixes the root cause. - Preserve behavior and interfaces unrelated to this diagnostic. - Reuse existing project components, utilities, and conventions. - Do not introduce render-phase side effects, render-phase state updates, or Hooks rule violations. - Preserve resource ownership and cleanup. Do not move work into a hotter render or frame path. - Adapt identifiers and framework details instead of copying blindly. - Do not disable the rule or suppress matching code. - Confirm this rule is enabled for the project: react. Verification: - Run focused tests for the changed behavior. - Run React Doctor and confirm this diagnostic no longer appears. - Report the files changed and any checks you could not run.

More Performance rules from the rules reference:

react-doctor/no-usememo-simple-expression: Remove useMemo — property access, math, and ternaries are already cheap without memoization
react-doctor/prefer-dynamic-import: Use `const Component = dynamic(() => import('library'), { ssr: false })` from next/dynamic or React.lazy()
react-doctor/prefer-motion-transform-property: Motion individual transforms miss compositor acceleration
react-doctor/prefer-stable-empty-fallback: Hoist a module-level const EMPTY = [] (or {}) and use it as the || / ?? fallback so the memoised child sees a stable reference
react-doctor/r3f-cap-device-pixel-ratio: Unbounded device pixel ratio

react-doctor/no-unthrottled-scroll-mutation