JavaScript Best Practices

Comprehensive coding standards for JavaScript development, optimized for AI agents and LLMs. Contains 24 rules across 8 categories, prioritized by impact.

When to Apply

Reference these guidelines when:

• Writing vanilla JavaScript code
• Implementing async operations and promises
• Handling DOM manipulation
• Optimizing JavaScript performance
• Reviewing code for security issues
• Working with ES modules and modern features

Rule Categories by Priority

Priority	Category	Impact	Prefix
1	Performance	CRITICAL	perf-
2	Async Patterns	CRITICAL	async-
3	Security	HIGH	security-
4	Error Handling	HIGH	error-
5	ES Modules	MEDIUM-HIGH	module-
6	Data Structures	MEDIUM	data-
7	DOM Manipulation	MEDIUM	dom-
8	Modern Features	LOW-MEDIUM	modern-

Quick Reference

1. Performance (CRITICAL)

• perf-avoid-memory-leaks - Clean up event listeners and intervals
• perf-dom-batch-updates - Batch DOM updates with DocumentFragment
• perf-debounce-throttle - Debounce scroll/resize handlers
• perf-avoid-layout-thrashing - Separate reads and writes to DOM
• perf-web-workers - Use Web Workers for heavy computation

2. Async Patterns (CRITICAL)

• async-promise-all - Use Promise.all() for parallel operations
• async-promise-allsettled - Use allSettled() when some can fail
• async-error-boundaries - Handle promise rejections properly
• async-avoid-nested-promises - Flatten with async/await
• async-cancellation - Use AbortController for cancellable requests

3. Security (HIGH)

• security-no-innerhtml - Use textContent instead of innerHTML
• security-no-eval - Never use eval() or new Function()
• security-sanitize-user-input - Sanitize before DOM insertion
• security-csp-compliance - Write CSP-compliant code

4. Error Handling (HIGH)

• error-custom-errors - Create custom E...