Guide · Agent skill
How to use the Modern JavaScript Patterns agent skill
Updated · written with AI from the project's own documentation and checked against our catalogue data
The Modern JavaScript Patterns skill is a set of instructions that an AI agent loads so it writes and refactors JavaScript using ES6+ conventions such as async/await, destructuring, arrow functions, modules and functional patterns. This guide explains what the skill changes, how to install it, how to ask for it in plain language, and what to watch for. By the end you will be able to install the skill and steer your agent toward modern JavaScript when it writes or refactors code.
Modern JavaScript Patternswshobson/agents · MIT Download the skill Quick start
- 1Download the ZIP. Download the modern-javascript-patterns skill as a ZIP file from this page.
- 2Unzip into a skills folder. Unzip the file into ~/.claude/skills/ for personal use, or into .claude/skills/ inside your project.
- 3Or upload it in the Claude apps. Open Settings, go to Capabilities, then Skills, and upload the ZIP file.
- 4Make a natural request. Ask the agent to refactor, modernize or optimize a specific piece of JavaScript in plain words.
- 5Review the changes. Read the agent's edits and run your own tests, since the skill does not run code by itself.
What the Modern JavaScript Patterns skill makes the agent do
When the skill is installed, the agent follows modern JavaScript conventions when it writes or refactors JavaScript. The skill covers ES6+ syntax including async/await, destructuring, spread operators, arrow functions, promises, modules, iterators, generators and functional programming patterns.
The skill also gives the agent a checklist of best practices. Examples include preferring const, using optional chaining and nullish coalescing, avoiding data mutation, preferring array methods over traditional loops, and handling errors with try/catch around async/await. For deeper examples and common pitfalls such as this binding, promise anti-patterns and memory leaks, the agent can consult the reference documents bundled with the skill.
Install the skill from the ZIP download or the Claude apps
Download the skill as a ZIP file from this page. Then choose one of the following methods.
To install it for your user account, unzip the file into ~/.claude/skills/. To install it for a single project, unzip it into the .claude/skills/ folder inside that project.
You can also upload the skill in the Claude apps. Go to Settings, then Capabilities, then Skills, and upload the ZIP there.
- Personal install: unzip into ~/.claude/skills/
- Project install: unzip into .claude/skills/ in your project folder
- Claude apps: Settings → Capabilities → Skills, then upload the ZIP
Trigger the skill with natural requests
You do not need a special command. The skill is meant to apply when you ask for refactoring, modern patterns or optimization of JavaScript. Its description says it is used when refactoring legacy code, implementing modern patterns, or optimizing JavaScript applications.
Describe the job in ordinary words and name the code you want changed. Mentioning the style you want, such as async/await instead of promise chains, helps the agent pick the right guidance.
- Refactor this callback-based function to use async/await.
- Modernize this file: replace var with const or let and use arrow functions.
- Rewrite this loop as array methods without mutating the input.
- Review this JavaScript for optional chaining and nullish coalescing opportunities.
Example: a small modernization
The skill steers the agent toward concise ES6+ syntax. For example, a traditional function can be written as an arrow function, as in the snippet below. Ask the agent to apply the same kind of change across a file, and check each edit against the behaviour of the original code.
const add = (a, b) => a + b;What the skill needs and its safety limits
The skill lists no requirements. It does not run scripts and does not use the network, according to its listing. It does not run code or access outside services by itself. The agent may still read and edit the files you give it in the normal way, so review changes before you accept them.
The skill gives general guidance, not measured results. It does not include benchmarks, and it is not a substitute for profiling when performance is critical.
Tips and limits for better results
Give the agent the code and the goal together. Say whether you need the code to run in old environments, since the skill focuses on ES6+ conventions and you should confirm compatibility yourself.
The skill focuses on plain JavaScript. If your project needs TypeScript-specific typing guidance, this skill is not the right fit, even though it sits in a TypeScript plugin folder.
- Test refactored code, because the skill does not run tests for you.
- Ask for one file or function at a time to keep reviews manageable.
- Use it during code reviews to keep style consistent across a team.
What people use it for
- Converting callback-heavy Node or browser code to async/await with try/catch error handling.
- Replacing var declarations with const by default and let only where reassignment is needed.
- Rewriting loops as map, filter and reduce while avoiding mutation of input data.
- Adding optional chaining and nullish coalescing to code that reads nested properties and default values.
- Teaching students current JavaScript idioms by comparing old and new versions of a function.
Frequently asked questions
How do I install the modern JavaScript patterns skill?
Download the ZIP from this page and unzip it into ~/.claude/skills/ for personal use, or into .claude/skills/ inside a project. You can also upload the ZIP in the Claude apps under Settings, then Capabilities, then Skills.
Does the modern JavaScript patterns skill require anything else?
The skill lists no requirements. It does not run scripts and does not use the network, so it adds guidance and reference files only.
Is the modern JavaScript patterns skill free?
The skill is licensed under the MIT licence, as stated on this page. Check the licence file included with the source if you need the full terms.
Does this skill work for TypeScript?
No, not as a primary focus. The skill is aimed at plain JavaScript and ES6+ in general, even though it sits in a TypeScript plugin folder. If you need TypeScript typing guidance, use a skill built for that purpose.
Does the skill make my code faster?
The skill gives general advice on modern patterns, not measured benchmarks. For performance-critical work, profile your application and tune based on the results.
Why is my agent not using the skill?
Check that the skill folder is in ~/.claude/skills/ or your project's .claude/skills/, or that the ZIP was uploaded under Settings, Capabilities, Skills. Then make your request about refactoring, modernizing or optimizing JavaScript so it matches the skill's description.
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Our verdict
Use this skill if you are modernizing callback-heavy or var-based JavaScript, learning current idioms, or want consistent style guidance during reviews. Pick something else if you need TypeScript-specific typing help or measured performance tuning, since this skill gives general advice only.
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