Technical Notes
Quick reference notes on various programming concepts, patterns, and best practices I've learned along the way.
JavaScript & TypeScript
Closures & Lexical Scope
Understanding how closures work is fundamental to mastering JavaScript. They allow functions to access variables from their outer scope even after the outer function has returned.
TypeScript Generic Constraints
Generic constraints let you specify requirements for type parameters. Use 'extends' to ensure type safety while maintaining flexibility in your type definitions.
Promise.all vs Promise.allSettled
Promise.all fails fast on the first rejection, while Promise.allSettled waits for all promises to complete regardless of their outcome. Choose based on your error handling needs.
Optional Chaining Best Practices
Optional chaining (?.) simplifies accessing nested properties, but overuse can mask data structure problems. Use it judiciously and validate data at boundaries.
React Patterns
Custom Hooks for Logic Reuse
Extract common stateful logic into custom hooks. Prefix with 'use' and follow hooks rules. This promotes DRY principles and makes testing easier.
Compound Components Pattern
Compound components work together to form a complete UI. They share implicit state through context, providing a flexible and intuitive API for complex components.
Server vs Client Components
In Next.js App Router, components are server-side by default. Use 'use client' only when you need interactivity, browser APIs, or hooks like useState.
Error Boundaries for Resilience
Error boundaries catch JavaScript errors in their child component tree. Implement them to prevent entire app crashes and provide graceful fallback UIs.
Backend Architecture
RESTful API Design Principles
Follow REST conventions: use proper HTTP methods, meaningful URLs, appropriate status codes, and stateless communication. Version your APIs from the start.
Middleware Pattern in Node.js
Middleware functions have access to request, response, and next. They execute sequentially, allowing you to modularize cross-cutting concerns like auth and logging.
Authentication vs Authorization
Authentication verifies who you are (login), while authorization determines what you can do (permissions). Implement both with JWT tokens and role-based access control.
Rate Limiting Strategies
Protect your APIs with rate limiting. Use algorithms like token bucket or sliding window. Consider different limits for authenticated vs anonymous users.
SQL & Databases
Indexing for Performance
Indexes speed up reads but slow down writes. Index foreign keys, columns in WHERE clauses, and JOIN conditions. Monitor query plans to identify missing indexes.
N+1 Query Problem
Avoid loading related records in a loop. Use JOIN operations or eager loading in ORMs. A single query with JOIN is far more efficient than multiple separate queries.
Transaction Isolation Levels
Understand ACID properties and isolation levels (Read Uncommitted, Read Committed, Repeatable Read, Serializable). Choose based on consistency vs performance needs.
Database Normalization
Normalize to reduce redundancy and improve data integrity. Common forms: 1NF (atomic values), 2NF (no partial dependencies), 3NF (no transitive dependencies).
DevOps & Deployment
Container Best Practices
Use multi-stage builds to reduce image size. Run as non-root user. Keep images minimal. Use .dockerignore to exclude unnecessary files from context.
CI/CD Pipeline Stages
Typical stages: build, test, security scan, deploy to staging, integration tests, deploy to production. Fail fast and provide clear feedback.
Environment Configuration
Never hardcode secrets. Use environment variables and secret management tools. Keep dev, staging, and production configs separate but consistent.
Monitoring & Logging
Implement structured logging with appropriate levels. Use centralized logging services. Set up alerts for critical errors and performance degradation.
Git & Version Control
Commit Message Conventions
Write clear, descriptive commits using conventional commits format: type(scope): description. Common types: feat, fix, docs, refactor, test, chore.
Git Rebase vs Merge
Rebase creates a linear history by replaying commits on top of another branch. Merge preserves history with a merge commit. Use rebase for feature branches, merge for main.
Cherry-Pick for Selective Changes
Cherry-pick applies specific commits from one branch to another. Useful for hotfixes or selectively backporting features. Use sparingly to avoid duplicate commits.
Git Hooks for Automation
Git hooks automate tasks at different points in the git workflow. Pre-commit hooks can run linters, tests, or formatting. Use tools like husky for easy setup.
Want to discuss these topics?
I'm always eager to learn more and exchange knowledge. Feel free to reach out if you'd like to discuss any of these concepts or share your own insights.
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