Skills Guide

JavaScript Pro Expert

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Master modern JavaScript with ES6+, async patterns, and Node.js APIs. Handles promises, event loops, and browser/Node compatibility.

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Sby Skills Guide Bot
DevelopmentIntermediate
7/28/2026
Claude CodeCursorWindsurfCopilotCodex
#javascript#async#nodejs#es6#performance

Recommended for

Backend developerClaude CodeCode reviewFrontend developerCursorCopilot

Automated summary

This skill brings in a modern JavaScript expert to write, debug, and optimize ES6+ code that runs in Node.js and in the browser.

Strengths

  • Explicitly covers the async model: promises, async/await, the event loop, and the microtask queue
  • Delivers concrete outputs: error handling, race-condition prevention, module structure, and async Jest tests
  • Accounts for cross-environment compatibility with a polyfill strategy and bundle-size awareness
  • Includes guidance on TypeScript migration and type safety

Limitations

  • Does not address backend architecture or system design, only the JavaScript code itself
  • TypeScript coverage is limited to migration rather than advanced type design
  • No tooling or build-configuration specifics are provided, so you must supply them yourself
When to use it

Use it when you need to write or debug modern asynchronous JavaScript for Node.js or the browser, or modernize legacy code.

When not to use it

Skip it when the need is full TypeScript architecture, backend architecture decisions, or a non-JavaScript runtime.

Security analysis

Safe
Quality score72/100

Instruction-only JavaScript guidance skill; it declares no tools and contains no commands, file/network access, secret handling, or destructive behavior.

No concerns found

How this analysis is made

Examples

Debug async race condition
My Node.js service intermittently returns stale data from this Promise.all block — can you find the race condition and rewrite it with async/await and proper error handling?
Migrate legacy callbacks
Convert this legacy callback-based JavaScript module to modern ES6+ with async/await, clean exports, and JSDoc comments.
Browser compatibility pass
Review this browser JavaScript for cross-browser compatibility, suggest a polyfill strategy, and flag anything that hurts bundle size.

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. metadata: model: inherit risk: unknown source: community

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

Use this skill when

  • Building modern JavaScript for Node.js or browsers
  • Debugging async behavior, event loops, or performance
  • Migrating legacy JS to modern ES standards

Do not use this skill when

  • You need TypeScript architecture guidance
  • You are working in a non-JS runtime
  • The task requires backend architecture decisions

Instructions

  1. Identify runtime targets and constraints.
  2. Choose async patterns and module system.
  3. Implement with robust error handling.
  4. Validate performance and compatibility.

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.

From the file to a first result

The download contains exactly the content displayed on this page. This copy may differ from the latest version in the source repository.

View the source and supporting files

This download contains SKILL.md only. Any scripts, references, templates and dependencies are not included. Get the required files from the source, preserving their directory structure, before continuing.

1. Download the file

Download SKILL.md

From the root of a test project, save the file as .skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md, or use the command below. This folder is for inspecting the skill before installation.

Command for macOS/Linux or WSL: requires a POSIX shell and curl. On Windows without WSL, use the download button and create the folder manually.

mkdir -p '.skill-downloads/javascript-pro-expert-ms47vq9r' && curl --fail --show-error --location 'https://skills-guides.com/api/skills/javascript-pro-expert-ms47vq9r/download' --output '.skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md.part' && mv '.skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md.part' '.skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md'

2. Check prerequisites

Read SKILL.md before using it. If it references scripts or external services, inspect them and prepare the required access in your test environment.

No recognized prerequisites section in this file. This does not mean it is self-contained: libraries, tools and access requirements may be mentioned elsewhere in the content or source repository.

The platforms on this page are catalog indications. The paths below follow tool documentation; they do not prove this skill has been run in those tools. No minimum tool version is confirmed for this listing.

3. Load the skill

After inspection, copy the complete folder into your project using one of the commands below, then open a new tool session. The command stops if a folder with the same name already exists: compare the files before replacing it.

Claude Code
test -f '.skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md' && test -s '.skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md' && mkdir -p '.claude/skills' && test ! -e '.claude/skills/javascript-pro' && cp -R '.skill-downloads/javascript-pro-expert-ms47vq9r' '.claude/skills/javascript-pro'

Cursor
test -f '.skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md' && test -s '.skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md' && mkdir -p '.cursor/skills' && test ! -e '.cursor/skills/javascript-pro' && cp -R '.skill-downloads/javascript-pro-expert-ms47vq9r' '.cursor/skills/javascript-pro'

Codex
test -f '.skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md' && test -s '.skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md' && mkdir -p '.agents/skills' && test ! -e '.agents/skills/javascript-pro' && cp -R '.skill-downloads/javascript-pro-expert-ms47vq9r' '.agents/skills/javascript-pro'

OpenSkills

OpenSkills must already be installed. The local install/read procedure is checked with OpenSkills 1.5.0, which requires Node.js ≥ 20.6.0. Catalog slugs are not resolved automatically.

Official OpenSkills installation
openskills install './.skill-downloads/javascript-pro-expert-ms47vq9r'

openskills read 'javascript-pro-expert-ms47vq9r'

Reading should display the installed file content and its base directory. It does not run the skill or install its dependencies.

For an agent that reads AGENTS.md, then sync the index. This command changes AGENTS.md: review the diff before using it.

openskills sync

Manual method or another tool: attach SKILL.md to a conversation, or open it in an agent that can read files. Include any required supporting resources. No universal folder is recognized by every tool.

4. Try a first task

Use a short, synthetic input: an API endpoint, a small document or an interface brief. In a new conversation, attach the file or give the agent its path, then adapt this request:

Read .skill-downloads/javascript-pro-expert-ms47vq9r/SKILL.md and apply its instructions to this example: [describe a test input]. Identify any missing files, dependencies or access. Produce the result requested by the skill without inventing data or running unreviewed scripts.

Expected result: output matching the skill instructions, or a precise list of missing prerequisites. A read confirmation alone does not validate a first use. If an external resource is unavailable, that path remains untested.

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