January 2026 – DevQivo

How to Write Clean Code as a Junior Developer

The clean code habits that produce the biggest improvement early: naming, single responsibility, guard clauses, comments and error handling.

Scope, hoisting, the temporal dead zone, the classic loop bug, and what const actually protects — with a self-test at the end.

Full Ubuntu VPS deployment for Node.js: users, firewall, PM2, Nginx reverse proxy, free HTTPS, hardening and update scripts.

Twelve SQL mistakes that return wrong answers or destroy performance, from NULL handling to LEFT JOIN filtering and missing indexes.

Build fully responsive layouts with Grid, Flexbox, clamp(), container queries and custom properties instead of a CSS framework.

REST APIs explained from scratch: resources, HTTP methods, status codes, statelessness, authentication and good API design.

A practical Git branching workflow for teams of two to six: naming, commits, pull requests, merge strategies and conflict handling.

A feature-based React folder structure that scales, with path aliases, barrel files, and where API calls and state really belong.

Why CORS errors happen, what preflight requests are, and how to fix them properly on the server instead of disabling browser security.