The Codikko blog
Short, visual explainers for the ideas that trip up self taught developers. Step through each one, then go deeper in the lesson it comes from.
401 vs 403, the difference in one request
401 means the server doesn't know who you are; 403 means it does, and the answer is no. Watch one request hit both gates.
Express middleware explained, step by step
Middleware is a line of functions every request walks before your handler. Watch three stations stamp one request in order, then a missing token stop it early.
How the Node event loop works, visually
Node runs on one thread yet never blocks. Watch one async callback wait in the queue and get pushed onto the call stack to see how.
HTTP status codes, the eight you need
You don't need dozens of status codes. Watch one request get 200, 301, 401, 404 and 500, learn the first digit rule, and keep the eight that cover real traffic.
JWT vs session authentication, which one to pick
Sessions can be revoked; JWTs verify themselves. Watch one request take each path, then pick the trade-off that fits what you are building.
What "port 3000 already in use" actually means
EADDRINUSE means a process is still listening on that port. Watch one machine give door 3000 to the first process, refuse the second, then fix it both ways.