Mastering JavaScript Internals#2 The Parser & AST

The Parser: How JavaScript Actually Reads Your Code You type some JavaScript. You hit run. And it works. But between those two moments, something fascinating happens — your code gets read, understood, and transformed before a single instruction executes. That process is called parsing, and it's the very first thing the engine does. Let's walk through it, step by step. 🗺️ The Big Picture: 3 Steps Before Execution When the JavaScript engine receives your code, it does three things in order: Your C