`react-doctor/no-create-object-url-in-render`

Object URL is created during render

Category: Bugs
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-create-object-url-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 = ({ file }) => <img src={URL.createObjectURL(file)} alt="" />;

Corrected pattern

const Preview = ({ file }) => {
  const [url, setUrl] = useState("");
  useEffect(() => {
    const nextUrl = URL.createObjectURL(file);
    setUrl(nextUrl);
    return () => URL.revokeObjectURL(nextUrl);
  }, [file]);
  return <img src={url} alt="" />;
};

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-create-object-url-in-render diagnostic in the current repository. Required change: - Create object URLs in an effect or event handler and revoke each URL when it is replaced or no longer needed.

Reference transformation:Before:

const Preview = ({ file }) => <img src={URL.createObjectURL(file)} alt="" />;

After:

const Preview = ({ file }) => {
  const [url, setUrl] = useState("");
  useEffect(() => {
    const nextUrl = URL.createObjectURL(file);
    setUrl(nextUrl);
    return () => URL.revokeObjectURL(nextUrl);
  }, [file]);
  return <img src={url} alt="" />;
};

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. - 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 Bugs rules from the rules reference:

react-doctor/no-create-ref-in-function-component: createRef in function component
react-doctor/no-create-store-in-render: Hoist the store/atom/observable construction to module scope: const store = create(...) outside the component.
react-doctor/no-danger-with-children: Use either children or dangerouslySetInnerHTML on an element, never both.
react-doctor/no-deprecated-keyboard-event-keycode-which: Deprecated KeyboardEvent keyCode or which
react-doctor/no-derived-state: Disallow storing derived state in an effect.

react-doctor/no-create-object-url-in-render