Explore the inner workings of JavaScript runtimes in this Node Congress 2023 conference talk. Delve into the magic behind Node.js Core and understand why new JavaScript runtimes like Bun and Deno are gaining popularity. Learn how to create a JavaScript runtime from scratch by examining key components of Node.js, including the relationship between Chrome's V8 engine and Libuv. Discover what makes one JavaScript runtime superior to others as you follow along with practical examples using C++. Gain insights into JavaScript engines, the role of Libuv in Node.js, and the step-by-step process of building a custom JS runtime.