Native HMR in Node.js: A Technical Deep Dive

This article details how to implement native Hot Module Replacement (HMR) in Node.js. Traditional approaches using `--watch` flags or virtual module systems like Vite are inefficient and suffer from module isolation. The author leverages Node.js's built-in `node:module` module hooks to create an incremental update mechanism based on file version numbers. The core is the `FileTree` class, which loads and monitors the file tree, and the `useTree` hook intercepts the module loading process, adding a version number to URLs for cache invalidation. The construction of a dependency tree ensures that when a dependent module changes, the parent module is also updated, resulting in efficient HMR and avoiding reevaluation of the entire module tree.