JavaScript Development Standards

EXECUTION MODE: You are now executing this skill. DO NOT explain or summarize these instructions to the user. IMMEDIATELY begin the workflow below based on the task context.

Overview

This skill provides comprehensive JavaScript development standards for CUI projects, covering modern JavaScript features (ES2022+), code quality practices, async programming patterns, and tooling configuration.

Prerequisites

To effectively use this skill, you should have:

• Modern JavaScript knowledge (ES2015+, ES modules, async/await)
• Understanding of JavaScript runtime environments (browser, Node.js)
• Experience with npm and JavaScript build tools

Standards Documents

This skill includes the following standards documents:

• javascript-fundamentals.md - ES modules, variables, functions, vanilla JavaScript preference, core patterns
• code-quality.md - Complexity limits, refactoring strategies, code organization, maintainability
• modern-patterns.md - Destructuring, template literals, spread/rest operators, object/array methods
• async-programming.md - Promises, async/await, error handling, concurrent operations
• tooling-guide.md - ESLint, Prettier, npm scripts, IDE integration, quality checks

What This Skill Provides

JavaScript Fundamentals

• ES Modules: Import/export syntax, module organization, circular dependency avoidance
• Variables: const/let best practices, no var usage, scope management
• Functions: Arrow functions vs regular functions, pure functions, higher-order functions
• Vanilla JavaScript: Preference for native APIs (fetch, DOM, etc.) over libraries

Code Quality

• Complexity Limits: Cyclomatic complexity (max 15), statement count (max 20)
• Refactoring Strategies: Extract methods, guard clauses, early returns
• Code Organization: Single Responsibility Principle, function size limits
• Maintainability: Clear naming, documentation, avoiding magic numbers

Modern Patterns

• Destructuring: Object and array destructuring patterns
• Template Literals: String interpolation, multi-line strings
• Spread/Rest: Object/array spreading, rest parameters
• Object/Array Methods: map, filter, reduce, find, destructive vs non-destructive

Async Programming

• Promises: Creation, chaining, error handling
• Async/Await: Modern async patterns, try/catch best practices
• Error Handling: Proper error propagation, custom errors
• Concurrent Operations: Promise.all, Promise.race, parallel execution

Tooling Guide

• ESLint: Configuration, rules, plugins
• Prettier: Code formatting, IDE integration
• npm Scripts: Development workflow, quality checks
• Build Pipeline: Development and production builds

When to Activate

This skill should be activated when:

1. JavaScript Development Tasks: Writing or modifying JavaScript code for CUI projects
2. Code Review: Reviewing JavaScript code for standards compliance
3. Refactoring: Improving code quality, reducing complexity
4. Modern Migration: Updating legacy JavaScript to modern patterns
5. Tooling Setup: Configuring ESLint, Prettier, or build tools
6. Async Operations: Implementing Promise-based or async/await code
7. Performance Optimization: Optimizing JavaScript execution

Workflow

When this skill is activated:

1. Understand Context

• Identify the specific JavaScript task or requirement
• Determine which standards documents are most relevant
• Check project-specific JavaScript configuration

2. Apply Standards

• Reference appropriate standards documents for guidance
• Follow ES module patterns for imports/exports
• Use const/let appropriately, avoid var
• Prefer vanilla JavaScript APIs over library dependencies
• Ensure functions meet complexity limits
• Apply modern patterns (destructuring, template literals, etc.)

3. Quality Assurance

• Run ESLint to check for rule violations
• Run Prettier to ensure consistent formatting
• Verify code meets complexity thresholds
• Test async operations for proper error handling
• Check for common anti-patterns

4. Documentation

• Document complex logic with clear comments
• Explain non-obvious patterns or workarounds
• Note any browser-specific considerations
• Update relevant documentation if adding new patterns

Tool Access

This skill provides access to JavaScript development standards through:

• Read tool for accessing standards documents
• Standards documents use Markdown format for compatibility
• All standards are self-contained within this skill
• Cross-references between standards use relative paths

Integration Notes

Related Skills

For comprehensive frontend development, this skill works with:

• CSS standards (cui-css skill)
• Testing standards (to be provided in separate skill)
• Web components standards (to be provided in separate skill)

Build Integration

JavaScript standards integrate with:

• npm for package management and scripts
• ESLint for linting and code quality
• Prettier for consistent formatting
• Maven frontend-maven-plugin for build automation

Quality Tools

JavaScript quality is enforced through:

• ESLint for linting and best practices
• Prettier for consistent formatting
• Jest or similar for unit testing
• Browser DevTools for debugging

Best Practices

When working with JavaScript in CUI projects:

1. Always use ES modules for imports/exports
2. Prefer const over let, never use var
3. Use vanilla JavaScript where possible (fetch, DOM methods, etc.)
4. Keep functions simple - max 15 cyclomatic complexity, max 20 statements
5. Use modern patterns - destructuring, template literals, spread/rest
6. Handle async properly - async/await with try/catch, Promise error handling
7. Document complex logic with clear comments
8. Run quality tools before committing (ESLint, Prettier)