High Performance Browser Networking
This book is just flipping fantastic. Starting from the very bottom of the layers (touching on the physical with pragmatic intelligence), going up through TCP/UDP, TLS, HTTP/1+2+3, and various Browser APIs (XmlHttpRequest, WebSocket, WebRTC, etc.), this book is a phenomenal primer on … how the web works. Understanding all of these layers in tandem is extremely complex but Ilya gives a number of reasonable and reliable insights into managing client/server interactions and their side effects effectively. One of the books I believe every developer ought to have / read.