mcp4openapi: Skill for Claude Code

.claude/skills/javascript-es2022/SKILL.md

javascript-es2022 is a skill for Claude Code from davidruzicka/mcp4openapi. It costs 59 tokens per session (387 once invoked), scanned A, original, MIT.

JavaScript coding rules for .js, .mjs, and .cjs files, using modern Node.js 20 or newer features. They cover code style, dependencies, asynchronous code, and tests.

In plain words
What is it for?
Use them when implementing or refactoring JavaScript in the repository. They guide module format, naming, error handling, async code, and Vitest tests.
Why use it?
They give the coding agent consistent expectations for changing JavaScript files. This helps avoid incompatible syntax, unnecessary packages, and missing tests.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is davidruzicka/mcp4openapi's own configuration. It tells Claude Code how to work on mcp4openapi itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mcp4openapi configures →

Reuse

Borrowing it

Nothing to install: this file belongs to davidruzicka/mcp4openapi. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/davidruzicka/mcp4openapi/main/.claude/skills/javascript-es2022/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/davidruzicka/mcp4openapi

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for javascript-es2022

README.md
[![agentmods](https://agentmods.dev/badge/skills/davidruzicka/mcp4openapi/javascript-es2022/github.svg)](https://agentmods.dev/skills/davidruzicka/mcp4openapi/javascript-es2022)
Your own site
<a href="https://agentmods.dev/skills/davidruzicka/mcp4openapi/javascript-es2022"><img src="https://agentmods.dev/badge/skills/davidruzicka/mcp4openapi/javascript-es2022/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for javascript-es2022

Your own site · 80×15
<a href="https://agentmods.dev/skills/davidruzicka/mcp4openapi/javascript-es2022"><img src="https://agentmods.dev/badge/skills/davidruzicka/mcp4openapi/javascript-es2022.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 387 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00059 $0.00387
Opus 5.5 $0.00024 $0.00155
Sonnet 5.5 $0.00012 $0.00077
Haiku 4.5 $0.00006 $0.00039

Measured 1mo ago against content hash f905136f7dbe, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

javascript-es2022 scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/javascript-es2022/SKILL.md · 37 lines

What it actually says

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.
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 37 lines · 59 tokens per session scan A f905136f7dbe

Subscribe to this mod's changes

javascript-es2022 is a skill published in the GitHub repository davidruzicka/mcp4openapi (0 stars, last pushed 4d ago), licensed MIT. It adds 59 tokens to every session and 387 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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