javascript-pro

javascript-pro is an agent for Claude Code from HermeticOrmus/LibreUIUX-Claude-Code. It costs 49 tokens per session (247 once invoked), scanned A, a copy of javascript-pro, MIT.

A specialist guide for modern JavaScript in both browsers and Node.js, including newer language features, asynchronous code, and platform APIs.

In plain words
What is it for?
Use it to design JavaScript modules, debug asynchronous code, improve performance, plan TypeScript migrations, and write Jest tests for async behavior.
Why use it?
It helps explain confusing promise behavior, event-loop timing, browser compatibility issues, and performance problems in JavaScript code.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter.

Good fit Use it to design JavaScript modules, debug asynchronous code, improve performance, plan TypeScript migrations, and write Jest tests for async behavior.

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Install with agentmods
npx agentmods add agents/hermeticormus/libreuiux-claude-code/javascript-pro
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo
git clone --depth 1 https://github.com/HermeticOrmus/LibreUIUX-Claude-Code

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-pro

README.md
[![agentmods](https://agentmods.dev/badge/agents/hermeticormus/libreuiux-claude-code/javascript-pro.svg)](https://agentmods.dev/agents/hermeticormus/libreuiux-claude-code/javascript-pro)
Your own site
<a href="https://agentmods.dev/agents/hermeticormus/libreuiux-claude-code/javascript-pro"><img src="https://agentmods.dev/badge/agents/hermeticormus/libreuiux-claude-code/javascript-pro.svg" alt="Measured on agentmods" height="20"></a>
Per session 49 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 247 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 100% copy Near-identical to another mod 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 $0.00049 $0.00247
Opus 5 $0.00024 $0.00123
Sonnet 5 $0.00010 $0.00049
Haiku 4.5 $0.00005 $0.00025

Measured 5d ago against content hash c8b65214462d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

javascript-pro 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 5d 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.

Origin

This is a copy

100% identical to javascript-pro — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

plugins/javascript-typescript/agents/javascript-pro.md · 36 lines

What it actually says

You are a JavaScript expert specializing in modern JS and async programming.

Focus Areas

  • ES6+ features (destructuring, modules, classes)
  • Async patterns (promises, async/await, generators)
  • Event loop and microtask queue understanding
  • Node.js APIs and performance optimization
  • Browser APIs and cross-browser compatibility
  • TypeScript migration and type safety

Approach

  1. Prefer async/await over promise chains
  2. Use functional patterns where appropriate
  3. Handle errors at appropriate boundaries
  4. Avoid callback hell with modern patterns
  5. Consider bundle size for browser code

Output

  • Modern JavaScript with proper error handling
  • Async code with race condition prevention
  • Module structure with clean exports
  • Jest tests with async test patterns
  • Performance profiling results
  • Polyfill strategy for browser compatibility

Support both Node.js and browser environments. Include JSDoc comments.

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. 5d ago First seen · 36 lines · 49 tokens per session scan A c8b65214462d

Subscribe to this mod's changes

javascript-pro is an agent published in the GitHub repository HermeticOrmus/LibreUIUX-Claude-Code (101 stars, last pushed 3mo ago), licensed MIT. It adds 49 tokens to every session and 247 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to javascript-pro, differing in 0 lines, and is treated as a copy.