`react-doctor/no-fill-map-element-as-key`

fill().map() first param is the element, not the index

Category: Bugs
Severity: warn
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/no-fill-map-element-as-key. 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

{Array(3).fill(null).map((item) => <Row key={item} />)}

Corrected pattern

const slotIds = ["primary", "secondary", "tertiary"];
const rows = slotIds.map((slotId) => <Row key={slotId} />);

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-fill-map-element-as-key diagnostic in the current repository. Required change: - Do not key children from a repeated .fill() value. Derive each key from stable item identity.

Reference transformation:Before:

{Array(3).fill(null).map((item) => <Row key={item} />)}

After:

const slotIds = ["primary", "secondary", "tertiary"];
const rows = slotIds.map((slotId) => <Row key={slotId} />);

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/no-find-dom-node: Use refs (useRef/createRef) to access DOM nodes instead of the removed findDOMNode API.
react-doctor/no-fixed-inside-transformed-ancestor: Fixed element is scoped by a transformed ancestor
react-doctor/no-floating-then-in-jsx-handler: Floating .then in a JSX event handler
react-doctor/no-hydration-branch-on-browser-global: Render the same initial branch on the server and client instead of branching on a browser global during hydration.
react-doctor/no-impure-call-at-module-scope: Nondeterministic built-in at module scope

react-doctor/no-fill-map-element-as-key