# `react-doctor/jsx-filename-extension`

Use .jsx / .tsx (or your project's chosen extension) for files containing JSX.

- **Status:** Active
- **Category:** Architecture
- **Assessment:** Evidence-required risk
- **Required evidence:** source code, repository context
- **Default configuration:** Disabled until configured
- **Default severity:** warn
- **Scope:** All supported frameworks
- **Active when:** off by default (opt-in)
- **Requirements:** react
- **Priority:** 13 (P3)
- **Source:** oxlint-plugin-react-doctor
- **Rule set:** oxlint-plugin-react-doctor 0.9.3 (prompt schema 2)
- **Documentation:** [Official documentation](https://oxc.rs/docs/guide/usage/linter/rules/react/jsx-filename-extension)

## Validation prompt

Confirm the detector match and collect the required evidence before deciding whether an edit is warranted.

Fires when a JSXElement or JSXFragment appears in a file whose extension is not in the allowed set (default `.jsx`, `.tsx`), reporting once per file on the first JSX node. In `allow: "as-needed"` mode it additionally fires on an allowed-extension file that contains zero JSX: unless `ignoreFilesWithoutCode` is set and the file has no non-comment statements.

Suppress when: this is a pure filename-convention check, so JSX in a `.js` file is flagged even though setups like Next.js and Create React App compile JSX in `.js` out of the box: suppress when the project intentionally allows JSX in that extension. (Note: Vite/esbuild is NOT such a setup: it errors on JSX in `.js` by default and effectively agrees with this rule.)

## Evidence boundary

The diagnostic proves only that the detector's modeled source pattern matched. It does not prove runtime impact, product intent, rendered failure, or that one remediation is correct.

Establish the environment, explicit repository policy, relevant exceptions, and required rendered or runtime evidence before deciding the occurrence. This page’s Assessment and Required evidence fields define the review contract.

Default severity is registry metadata. Use the occurrence's JSON severity after repository configuration when ordering real findings.

Record one outcome:

- **Confirmed failure:** The required evidence establishes the violation.
- **Rejected:** A documented exception or false-positive predicate applies.
- **Needs evidence:** Named evidence can still be collected.
- **Unavailable:** Required evidence cannot be collected in this run.
- **Waived with evidence:** An authorized, scoped exception applies to an established failure.
- **Observation:** The review records an optional tradeoff without claiming a defect.

A waiver records its scope, authority, evidence, and review or expiry condition. It is not a pass or false positive.

## Fix prompt

Apply this candidate correction only after the required evidence confirms the risk.

Rename the file to an allowed JSX extension so its contents match its name: e.g. `Button.js` -> `Button.tsx` (or `.jsx` for plain JS), updating any imports that reference the old path. If your toolchain intentionally permits JSX in `.js`/`.ts`, instead add that extension under this port's setting `settings["react-doctor"].jsxFilenameExtension.extensions` (e.g. `extensions: ["js", "jsx", "tsx"]`) rather than renaming. See https://oxc.rs/docs/guide/usage/linter/rules/react/jsx-filename-extension

## Repository-wide copy prompt

Use this only for a repository-wide pass after validating each occurrence. For one occurrence, use the occurrence-level guidance above.

````text
Fix every confirmed `react-doctor/jsx-filename-extension` diagnostic in the current repository.

Required change:
- Rename the file to an allowed JSX extension so its contents match its name: e.g. `Button.js` -> `Button.tsx` (or `.jsx` for plain JS), updating any imports that reference the old path. If your toolchain intentionally permits JSX in `.js`/`.ts`, instead add that extension under this port's setting `settings["react-doctor"].jsxFilenameExtension.extensions` (e.g. `extensions: ["js", "jsx", "tsx"]`) rather than renaming. See https://oxc.rs/docs/guide/usage/linter/rules/react/jsx-filename-extension.

Validation before editing:
Fires when a JSXElement or JSXFragment appears in a file whose extension is not in the allowed set (default `.jsx`, `.tsx`), reporting once per file on the first JSX node. In `allow: "as-needed"` mode it additionally fires on an allowed-extension file that contains zero JSX: unless `ignoreFilesWithoutCode` is set and the file has no non-comment statements.

Suppress when: this is a pure filename-convention check, so JSX in a `.js` file is flagged even though setups like Next.js and Create React App compile JSX in `.js` out of the box: suppress when the project intentionally allows JSX in that extension. (Note: Vite/esbuild is NOT such a setup: it errors on JSX in `.js` by default and effectively agrees with this rule.)

Constraints:
- 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: `off by default (opt-in)`.

Assessment:
- Record detector evidence, applicability facts, assumptions, missing evidence, and the rule class for this occurrence.
- Return one outcome: Confirmed failure, Rejected, Needs evidence, Unavailable, Waived with evidence, or Observation.
- A waiver records the established failure, scope, authority, evidence, and review or expiry condition. It is not a pass or false positive.

Verification:
- Run focused tests for the changed behavior.
- Run React Doctor and confirm this diagnostic no longer appears from changed code.
- Run an unfiltered scan of the affected scope before claiming no cross-category regression.
- Report the files changed and any checks you could not run.
````