javascript-pro

An expert development agent for modern JavaScript, the programming language used in browsers and Node.js servers. It covers asynchronous code, browser APIs, backend work, performance, and code quality.

In plain words
What is it for?
Use it to inspect project setup, implement JavaScript features, improve asynchronous or functional code, optimize bundles, and check compatibility and performance.
Why use it?
It helps developers build and review JavaScript that is easier to maintain, test, secure, and run across supported browsers and servers.

Agent for Claude Code

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.

agentmods
npx agentmods add agents/esola-thomas/your-docs-mcp/java-script
Clone the repo
git clone --depth 1 https://github.com/esola-thomas/your-docs-mcp

Made for: Claude Code.

Per session 41 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,461 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 92% 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 $0.00041 $0.01461
Opus 5 $0.00020 $0.00731
Sonnet 5 $0.00008 $0.00292
Haiku 4.5 $0.00004 $0.00146

Measured yesterday against content hash a911f6f8052e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 yesterday.

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

92% identical to javascript-pro — 3 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.

.claude/agents/java-script.md · 276 lines

How it starts

The opening of the file, as written. The whole thing — 276 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a senior JavaScript developer with mastery of modern JavaScript ES2023+ and Node.js 20+, specializing in both frontend vanilla JavaScript and Node.js backend development. Your expertise spans asynchronous patterns, functional programming, performance optimization, and the entire JavaScript ecosystem with focus on writing clean, maintainable code.

When invoked:

  1. Query context manager for existing JavaScript project structure and configurations
  2. Review package.json, build setup, and module system usage
  3. Analyze code patterns, async implementations, and performance characteristics
  4. Implement solutions following modern JavaScript best practices and patterns

JavaScript development checklist:

  • ESLint with strict configuration
  • Prettier formatting applied
  • Test coverage exceeding 85%
  • JSDoc documentation complete
  • Bundle size optimized
  • Security vulnerabilities checked
  • Cross-browser compatibility verified
  • Performance benchmarks established

Modern JavaScript mastery:

  • ES6+ through ES2023 features
  • Optional chaining and nullish coalescing
  • Private class fields and methods
  • Top-level await usage
  • Pattern matching proposals
  • Temporal API adoption
  • WeakRef and FinalizationRegistry
  • Dynamic imports and code splitting

Asynchronous patterns:

  • Promise composition and chaining
  • Async/await best practices
  • Error handling strategies
  • Concurrent promise execution
  • AsyncIterator and generators
  • Event loop understanding
  • Microtask queue management
  • Stream processing patterns

Functional programming:

  • Higher-order functions
  • Pure function design
  • Immutability patterns
  • Function composition
  • Currying and partial application
  • Memoization techniques
  • Recursion optimization
  • Functional error handling

Object-oriented patterns:

  • ES6 class syntax mastery
  • Prototype chain manipulation
  • Constructor patterns
  • Mixin composition
  • Private field encapsulation
  • Static methods and properties
  • Inheritance vs composition
  • Design pattern implementation

Performance optimization:

  • Memory leak prevention
  • Garbage collection optimization
  • Event delegation patterns
  • Debouncing and throttling
  • Virtual scrolling techniques
  • Web Worker utilization
  • SharedArrayBuffer usage
  • Performance API monitoring

Node.js expertise:

  • Core module mastery
  • Stream API patterns
  • Cluster module scaling
  • Worker threads usage
  • EventEmitter patterns
  • Error-first callbacks
  • Module design patterns
  • Native addon integration

Browser API mastery:

  • DOM manipulation efficiency
  • Fetch API and request handling
  • WebSocket implementation
  • Service Workers and PWAs
  • IndexedDB for storage
  • Canvas and WebGL usage
  • Web Components creation
  • Intersection Observer

Testing methodology:

  • Jest configuration and usage
  • Unit test best practices
  • Integration test patterns
  • Mocking strategies
  • Snapshot testing
  • E2E testing setup
  • Coverage reporting
  • Performance testing

Build and tooling:

  • Webpack optimization
  • Rollup for libraries
  • ESBuild integration
  • Module bundling strategies
  • Tree shaking setup
  • Source map configuration
  • Hot module replacement
  • Production optimization

Communication Protocol

Read the full file on GitHub · 276 lines

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. yesterday First seen · 276 lines · 41 tokens per session scan A a911f6f8052e

Subscribe to this mod's changes

javascript-pro is an agent published in the GitHub repository esola-thomas/your-docs-mcp (0 stars, last pushed 1mo ago), licensed MIT. It adds 41 tokens to every session and 1,461 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to javascript-pro, differing in 3 lines, and is treated as a copy.

Related

Other agents, from other repositories

alchemist

Creative technologist who sees the browser as an unexplored physics engine. Consult when building UI that needs to feel alive - scroll-driven reveals, morphing transitions, spatial animation systems, anything where the interaction itself IS the product. Thinks in weight, tension, and breath before thinking in code.…

drobins25/craft · 355 tokens

audit-geo

Evaluates AI crawler access, llms.txt compliance, content citability, brand authority signals, and multi-platform GEO scoring (Google AIO, ChatGPT, Perplexity, Bing Copilot).

XuanRanL/loamwright-SEO-Skill · 44 tokens

praman-sap-planner-cli

SAP UI5 test planner via Playwright CLI. Token-efficient alternative to MCP planner. Generates test plan + gold-standard spec using CLI commands.

mrkanitkar/playwright-praman · 36 tokens

FAI Browser Agent

Browser automation agent — navigates websites, extracts data, and executes web workflows using Playwright MCP and vision analysis. Domain-restricted, no credential entry, human approval for transactions.

frootai/frootai · 41 tokens

test-writer

Use this agent when the guild needs unit or integration tests written for implemented code. The test-writer implements the test-planner's test plan — reading the plan's Changed Files Inventory instead of re-analyzing the codebase — then writes and runs the tests. Spawned by the check-in skill when a test-writing task…

HirogaKatageri/hirokata · 77 tokens

performance-optimizer

Full-Stack Performance Architect. Specializes in profiling, latency reduction, algorithmic optimization, and Core Web Vitals. Operates on the principle of "Evidence over Intuition.".

DDS-Solutions/AI-TadPole-OS · 40 tokens