`react-doctor/waapi-animation-in-render`

Web Animation starts during render

Category: Bugs
Severity: error
Source: oxlint-plugin-react-doctor
Framework: global
Enabled when: always
Default: Enabled

Validate the diagnostic

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

Confirm the reported code matches react-doctor/waapi-animation-in-render. 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 { useRef } from "react";

const Card = ({ keyframes, options }) => {
  const elementRef = useRef<HTMLDivElement>(null);
  elementRef.current?.animate(keyframes, options);
  return <div ref={elementRef} />;
};

Corrected pattern

import { useEffect, useRef } from "react";

const Card = ({ keyframes, options }) => {
  const elementRef = useRef<HTMLDivElement>(null);
  useEffect(() => {
    const animation = elementRef.current?.animate(keyframes, options);
    return () => animation?.cancel();
  }, [keyframes, options]);
  return <div ref={elementRef} />;
};

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/waapi-animation-in-render diagnostic in the current repository. Required change: - Start element.animate() from an effect or interaction handler so React renders stay pure.

Reference transformation:Before:

import { useRef } from "react";

const Card = ({ keyframes, options }) => {
  const elementRef = useRef<HTMLDivElement>(null);
  elementRef.current?.animate(keyframes, options);
  return <div ref={elementRef} />;
};

After:

import { useEffect, useRef } from "react";

const Card = ({ keyframes, options }) => {
  const elementRef = useRef<HTMLDivElement>(null);
  useEffect(() => {
    const animation = elementRef.current?.animate(keyframes, options);
    return () => animation?.cancel();
  }, [keyframes, options]);
  return <div ref={elementRef} />;
};

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. - Adapt identifiers and framework details instead of copying blindly. - Do not disable the rule or suppress matching code. 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 Bugs rules from the rules reference:

react-doctor/web-animation-offsets-valid: Invalid Web Animation keyframe offsets
react-doctor/zustand-no-get-during-initialization: Zustand get() called during store initialization
react-doctor/zustand-no-mutating-state: Zustand state mutated in place
react-doctor/zustand-no-whole-store-destructure: Whole Zustand store subscribed during render
react-doctor/activity-wraps-effect-heavy-subtree: Audit the `<Activity>` subtree: every hide/show cycle tears down and recreates every `useEffect`/`useLayoutEffect` inside, so move subscriptions and effect-driven setState chains outside the boundary or pre-resolve the data above it.

react-doctor/waapi-animation-in-render