Claude-skill-registry lang-javascript

<skill_doc> <trigger_keywords>

Trigger Keywords

Activate this skill when the user mentions any of:

File Extensions:

.js

,

.mjs

,

.cjs

,

package.json

,

bun.lockb

JavaScript Core: JavaScript, ES2024, ES2025, ESM, CommonJS, import/export, async/await, Promise, Set methods, Object.groupBy, Map.groupBy, toSorted, toReversed, toSpliced

Runtime: Bun, Bun.serve, Bun.file, Bun.write, bun:sqlite, bun:test, Node.js alternative

Web Frameworks: Hono, hono/cors, hono/jwt, edge-first, Cloudflare Workers, c.json, c.text, middleware

Validation: Valibot, @hono/valibot-validator, v.object, v.string, v.pipe, schema validation

Testing: bun test, describe, it, expect, mock, beforeEach, afterEach, --coverage

Linting: Biome, biomejs, biome.json, linter, formatter, biome check

Database: bun:sqlite, Drizzle ORM, SQLite, prepared statements </trigger_keywords>

⛔ Forbidden Patterns

1. NO

   var

   : Always use

   const

   or

   let

   . Block scope is mandatory.
2. NO

   require

   in ESM: Use

   import

   /

   export

   syntax unless explicitly in a CJS context or interacting with legacy CJS-only packages in a compatible way.
3. NO Promise Constructors for Async/Await: Avoid

   new Promise()

   wrappers around functions that already return promises. Use

   async/await

   directly.
4. NO Loose Equality: Always use

   ===

   and

   !==

   instead of

   ==

   and

   !=

   .
5. NO Ignoring Floating Point Precision: Be aware of

   0.1 + 0.2 !== 0.3

   . Use libraries like

   decimal.js

   for financial calculations if needed.

🤖 Agent Tool Strategy

1. Discovery: Check for

   justfile

   first. If it exists, use

   just -l

   to list recipes and prefer

   just

   commands over language-specific CLIs (npm, cargo, poetry, etc.). Then, read

   package.json

   to understand the project type (

   type: "module"

   vs "commonjs"), dependencies, and scripts.
2. File Operations:
   • Use

     bun init

     or

     npm init

     (via Bash) only if creating a new project.
   • Use

     Read

     to inspect existing code before modifying.
3. Testing: Prefer running tests via

   bun test

   or

   npm test

   after changes to verify correctness.
4. Linting: Check for

   biome.json

   or

   eslint.config.js

   and respect the project's linting rules.

Quick Reference (30 seconds)

JavaScript ES2024+ Development Specialist - Modern JavaScript with Bun runtime and Hono framework.

Auto-Triggers:

.js

,

.mjs

,

.cjs

files,

package.json

, JavaScript projects

Core Stack:

• ES2024+: Set methods, Promise.withResolvers, immutable arrays, import attributes
• Bun: Fast all-in-one runtime, bundler, test runner, package manager
• Hono: Ultrafast, edge-first web framework
• Testing: Bun's built-in test runner
• Linting: Biome (linter + formatter)
• Validation: Valibot (tree-shakable)

Quick Commands:

# Create new project
bun init

# Install dependencies
bun install
bun add hono valibot
bun add -d @biomejs/biome

# Run development server
bun run --watch src/index.js

# Run tests
bun test

# Bundle for production
bun build ./src/index.js --outdir=./dist --target=bun

---

Implementation Guide (5 minutes)

See patterns.md for detailed implementation patterns covering:

• ES2024 Key Features (Set Operations, Promise.withResolvers)
• ES2025 Features (Import Attributes, RegExp.escape)
• Bun Runtime (File I/O, HTTP Server, SQLite)
• Hono Web Framework (Basic Setup, Validation, JWT, Error Handling)
• Testing with Bun
• Biome (Linter + Formatter)

Quick Troubleshooting

Bun Issues:

# Check version
bun --version

# Upgrade Bun
bun upgrade

# Clear cache
bun pm cache rm

Module System:

# Check package.json type
# (Use the Read tool to inspect package.json)

# ESM: "type": "module" - use import/export
# CommonJS: "type": "commonjs" or omitted - use require/module.exports

Common Fixes:

# Delete cache and reinstall
rm -rf node_modules bun.lockb && bun install

# Check for outdated packages
bun outdated

---

Advanced Patterns

For comprehensive documentation including advanced async patterns, module system details, performance optimization, and production deployment configurations, see:

• patterns.md - Implementation patterns (Bun, Hono, Biome)
• reference.md - Complete API reference, Context7 library mappings, Bun APIs
• examples.md - Production-ready code examples, full-stack patterns, testing templates

Context7 Integration

// Bun - mcp__context7__get_library_docs("/oven-sh/bun", "runtime bundler test", 1)
// Hono - mcp__context7__get_library_docs("/honojs/hono", "middleware validators routing", 1)
// Valibot - mcp__context7__get_library_docs("/fabian-hiller/valibot", "schema validation", 1)
// Drizzle - mcp__context7__get_library_docs("/drizzle-team/drizzle-orm", "queries migrations", 1)

---

Quick Troubleshooting

Bun Issues:

# Check version
bun --version

# Upgrade Bun
bun upgrade

# Clear cache
bun pm cache rm

Module System:

# Check package.json type
# (Use the Read tool to inspect package.json)

# ESM: "type": "module" - use import/export
# CommonJS: "type": "commonjs" or omitted - use require/module.exports

Common Fixes:

# Delete cache and reinstall
rm -rf node_modules bun.lockb && bun install

# Check for outdated packages
bun outdated

</skill_doc>