React & TypeScript linter setup

This skill handles project setup for the company ESLint stack: installing dependencies, adding config files, custom rules, and package.json scripts. For applying and enforcing rules on existing code, use a coding-standards or review skill when available.

When to use this skill

• User wants to install or configure ESLint in a React/TypeScript project.
• User asks to add lint scripts, devDependencies, or ESLint flat config.
• User wants custom rules (e.g. TODO ticket reference) or to migrate to the company config.
• User mentions "setup linter", "eslint config", "lint setup", "add eslint to project".

Prerequisites

• Project has a package.json (npm or yarn).
• Project has a tsconfig.json (or tsconfig.app.json) at the root — required for projectService: true in the config.
• Node.js 18+ (for ESLint 10 and flat config).

Setup checklist

Follow this order. Reference files are in assets/ and references/.

1. Dependencies

Install the listed devDependencies (see assets/package.json.snippet.json for example versions and structure). Prefer current compatible versions in real projects — the snippet is for illustration only. Merge into the project package.json or run:

yarn add -D eslint @eslint/js typescript-eslint eslint-plugin-react eslint-plugin-react-hooks eslint-plugin-testing-library globals

(or equivalent npm install -D ...). See references/dependencies-and-scripts.md for package list, example versions, and rationale.

2. ESLint config and TODO ticket rule (flat config — ESLint 9+)

• Copy assets/eslint.config.js to the project root (it includes the TODO ticket reference rule).
• Copy assets/eslint-rules/todo-ticket-ref.js to the repo (e.g. eslint-rules/todo-ticket-ref.js).
• Ensure globalIgnores match the project (e.g. dist, generated code). Adjust the rule pattern for your ticketing tool (e.g. JIRA) if needed.

3. Scripts

Add to package.json scripts (same as in assets/package.json.snippet.json; versions in that file are examples only):

"lint": "eslint .",
"lint:fix": "eslint . --fix"

Use yarn or npm consistently with the rest of the project.

4. Verify

• Run yarn lint or npm run lint.
• Fix any environment issues (missing tsconfig, wrong ignores, parser options).

See assets/README.md for file list and quick reference.

Rules applied (summary)

The default config applies common React/TypeScript rules:

• Coding: no-explicit-any, prefer-const, eqeqeq, no-nested-ternary, no-empty (catch), no-useless-catch, prefer-nullish-coalescing, consistent-indexed-object-style, max-depth
• React: no-array-index-key, jsx-fragments, react-hooks/*
• Tests: testing-library/prefer-screen-queries

Reference files

Rules of thumb

• One config at root: Use a single eslint.config.js at the project root (flat config).
• Match package manager: Use yarn or npm consistently for install and scripts.
• Ignore generated code: Add generated or third-party paths to globalIgnores to avoid noisy violations.
• TypeScript required: The config uses projectService: true; do not use this skill for non-TypeScript projects without adapting the config.