`react-doctor/three-no-object-construction-in-render`

Three.js object constructed during React render

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

Validate the diagnostic

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

Confirm the reported code matches react-doctor/three-no-object-construction-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

const Preview = () => {
  const material = new MeshStandardMaterial({ color: "tomato" });
  return <primitive object={material} />;
};

Corrected pattern

const Preview = () => {
  const material = useMemo(
    () => new MeshStandardMaterial({ color: "tomato" }),
    [],
  );
  return <primitive object={material} />;
};

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/three-no-object-construction-in-render diagnostic in the current repository. Required change: - Construct mutable Three.js objects in a stable initializer, effect, event, or module scope instead of recreating them during React render.

Reference transformation:Before:

const Preview = () => {
  const material = new MeshStandardMaterial({ color: "tomato" });
  return <primitive object={material} />;
};

After:

const Preview = () => {
  const material = useMemo(
    () => new MeshStandardMaterial({ color: "tomato" }),
    [],
  );
  return <primitive object={material} />;
};

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, three. 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/three-no-redundant-uniforms-need-update: Redundant uniformsNeedUpdate inside animation loop
react-doctor/three-no-state-in-animation-loop: React state update inside Three.js animation loop
react-doctor/three-no-state-in-pointer-move: React state update inside Three.js pointer-move handler
react-doctor/three-require-owned-geometry-cleanup: Locally owned Three.js geometry is not disposed
react-doctor/three-require-owned-material-cleanup: Locally owned Three.js material is not disposed

react-doctor/three-no-object-construction-in-render