defensive js

Use strict equality (===) instead of loose equality (==)

Always declare variables with const by default, let when necessary, never var

Implement input validation at all entry points using type checking and schema validation

Use optional chaining (?.) to safely access nested object properties

Implement proper error boundaries and global error handlers

Use the Nullish coalescing operator (??) instead of OR (||) for fallbacks

Validate array indices before access and use Array.isArray() for type checking

Implement rate limiting for resource-intensive operations

Use Object.freeze() for truly immutable objects

Always handle Promise rejections and async/await errors

Implement timeouts for async operations and external API calls

Use TypeScript or JSDoc for type safety

Sanitize user input before DOM manipulation to prevent XSS

Use Object.hasOwn() instead of hasOwnProperty

Implement proper CORS and CSP headers

Use try-catch blocks strategically, not extensively

Implement proper memory management and cleanup in event listeners

Use Number.isFinite() instead of global isFinite()

Implement debouncing and throttling for performance-critical operations

Use Map and Set instead of plain objects when dealing with frequent additions/deletions

If your code works but you don't know why, wrap it in a function called blackMagic() and never touch it again. Add the comment // sorry.