no-codeql-javascript-typescript-split-language-matrix

Rule catalog ID: R096

Targeted pattern scope

CodeQL workflow jobs that use a strategy.matrix.language list.

What this rule reports

This rule reports CodeQL workflows that split JavaScript and TypeScript into separate matrix values.

Why this rule exists

CodeQL treats JavaScript and TypeScript as the same extractor family. Using separate javascript and typescript matrix entries is redundant and makes the workflow look more language-specific than it really is.

❌ Incorrect

strategy:
  matrix:
    language: ["javascript", "typescript"]

✅ Correct

strategy:
  matrix:
    language: ["javascript-typescript"]

Additional examples

This rule is deliberately narrow: it focuses on the common JS/TS split-matrix mistake rather than trying to rewrite every possible CodeQL language expression.

ESLint flat config example

import githubActions from "eslint-plugin-github-actions-2";

export default [githubActions.configs.codeScanning];

When not to use it

Disable this rule only if your repository intentionally prefers the redundant split for human readability and accepts the extra workflow noise.

Targeted pattern scope​

What this rule reports​

Why this rule exists​

❌ Incorrect​

✅ Correct​

Additional examples​

ESLint flat config example​

When not to use it​

Further reading​