JavaScript is the language of the web. To truly master it, one must look beyond syntax and understand the runtime environment.
The Event Loop
Understanding the event loop is crucial for writing non-blocking code. JavaScript is single-threaded, but it handles concurrency through the callback queue and microtask queue.
Closures and Scope
Closures allow functions to retain access to variables from their containing scope even after the outer function has returned. This is the foundation of module patterns and data privacy in JS.
Prototypal Inheritance
Unlike classical inheritance, JavaScript uses prototypes. Understanding the prototype chain is key to effective object-oriented programming in JS.