JavaScript Engines & Runtime
Overview of how JavaScript engines work, runtime components, and why this matters for performance and behavior.
What this section covers
This category explains the pieces that make JavaScript run: engines (like V8), the runtime environment, and the event loop. You'll learn the difference between parsing, compilation, and execution and why it impacts performance tuning and debugging.
Why this matters to a developer
Understanding the runtime helps you write performant code and reason about async behavior, memory, and optimizations. It also clarifies why some language features exist and how they are implemented under the hood.
How to use this section
Start with How JavaScript Runs to get the big picture, then read Event Loop Deep Dive and JS Engine Internals for deeper mechanics.
🔗 Related:
FAQ
Q: Are engines the same across browsers?
A: No. Browsers use different engines (V8, SpiderMonkey, JavaScriptCore), but the ECMAScript standard ensures consistent language features.
Q: Does Node.js use the browser engine?
A: Node.js uses V8 for JS execution but provides different runtime APIs for I/O and system operations.
Topics in this section
Event Loop
A clear explanation of the JavaScript event loop, macrotasks vs microtasks, and how async code is scheduled.
JavaScript Engines (V8, SpiderMonkey, JavaScriptCore)
An overview of major JS engines, their architecture, and basic optimization techniques.
How JavaScript Runs
A high-level walkthrough of parsing, compilation, and execution phases in a JavaScript engine.
Compiler and Interpreter
Differences between interpreters and compilers in JS engines and why both are used.
Memory Management
High-level overview of memory allocation strategies and best practices for developers.
Browser vs Node Runtime
Differences between browser and Node runtimes, and how their environments affect APIs and behavior.