subagent Claude Code CX Codex Cursor

javascript-pro — Claude Code subagent: what it does, how to install

Q: How do I install javascript-pro in Claude Code?

Run `/plugin marketplace add wshobson/agents` or place `.claude/agents/javascript-pro.md` into your project directory.

Subagent for modern ES6+, async architecture, and Node.js or browser APIs. It catches race conditions and handles event loop edge cases.

Install into Claude Code · Plugin marketplace All methods and platforms ↓

/plugin marketplace add wshobson/agents
/plugin install javascript-typescript@claude-code-workflows

Open on GitHub

What javascript-pro does

This subagent focuses on modern JavaScript and asynchronous execution. It swaps nested promise chains for clean async/await, tracks microtask queue behavior, and generates JSDoc comments. It avoids callback hell. When writing browser code, it accounts for bundle size and polyfill strategies.

Output includes modular code, Jest async test suites, and performance profiling. It also assists with TypeScript migrations and proper error boundaries.

Use it when debugging tricky event loop bugs or building async pipelines. For a simple utility script, you will not need it.

What it helps with

refactor nested promise chains into clean async/await
debug race conditions across event loop microtasks
generate async Jest test suites with proper assertions
plan polyfill and bundle size strategies for browser code

Example prompts for the agent

Review this Node.js async pipeline and prevent race conditions
Refactor this module to ES6+ with JSDoc and async Jest tests
Check browser compatibility for this script and recommend polyfills

How to install javascript-pro

1Plugin marketplace

/plugin marketplace add wshobson/agents

/plugin install javascript-typescript@claude-code-workflows

2Manually: put the files in place

.claude/agents/javascript-pro.md

For all projects use ~/.claude/agents/. Claude delegates by the description field or an @-mention

Manually: put the files in place

.codex/agents/javascript-pro.md

Manually: put the files in place

.cursor/agents/javascript-pro.md

Cursor also reads .claude/agents/

Questions about javascript-pro

How do I install javascript-pro in Claude Code?

Run /plugin marketplace add wshobson/agents or place .claude/agents/javascript-pro.md into your project directory.

What does the javascript-pro subagent do?

It handles modern ES6+ syntax, async debugging, Node.js and browser APIs, plus Jest testing and TypeScript migration advice.

Does javascript-pro support browser environments?

Yes. It supports both Node.js and browsers, tracking bundle size impact and polyfill requirements.

Source text

javascript-pro.md · MIT

---
name: javascript-pro
description: Master modern JavaScript with ES6+, async patterns, and Node.js APIs. Handles promises, event loops, and browser/Node compatibility. Use PROACTIVELY for JavaScript optimization, async debugging, or complex JS patterns.
model: inherit
---

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.