# Javascript Es2022 > Use when implementing or refactoring JavaScript files (`.js`, `.mjs`, `.cjs`) in this repository. Applies Node.js 20+ ES2022 style, testing, and interaction rules from former `.github/instructions/javascript-es2022.instructions.md`. - Skill: `tomevault-io/javascript-es2022` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/javascript-es2022` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/javascript-es2022/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/javascript-es2022 --- # JavaScript ES2022 ## Coding standards - Use JavaScript with ES2022 features and Node.js (20+) ESM modules. - Use Node.js built-in modules and avoid external dependencies where possible. - Ask the user if additional dependencies are required before adding them. - Always use async/await for asynchronous code, and use `node:util` `promisify` to avoid callbacks. - Keep the code simple and maintainable. - Use descriptive variable and function names. - Do not add comments unless absolutely necessary; code should be self-explanatory. - Never use `null`; always use `undefined` for optional values. - Prefer functions over classes. ## Naming and style - Use PascalCase for classes, interfaces, enums, and type aliases; use camelCase for everything else. - Exception: snake_case is permitted for DTOs, API contracts, and configuration files where external formats dictate it. - Skip interface prefixes like `I`; rely on descriptive names. - Name things for behavior or domain meaning, not implementation details. ## Testing - Use Vitest for testing. - Write tests for all new features and bug fixes. - Ensure tests cover edge cases and error handling. - Never change production code to make it easier to test; test the real behavior. ## Documentation - When adding new features or making significant changes, update `README.md` where necessary. ## User interactions - Ask questions if implementation details or design choices are unclear. - Always answer in the same language as the question, but keep generated code, comments, and docs in English. --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/davidruzicka) — claim your Tome and manage your conversions.