I’m trying to understand npm’s file lookup behavior. When I run npm commands, it seems to find package.json files even when I’m not in the same folder as the file. For example, if I’m in a subfolder that doesn’t have its own package.json, npm still works and appears to be using a package.json from a parent directory somewhere up the tree. Does npm actually traverse up the directory structure looking for package.json files? And if this is true, does the same thing happen with require() when it’s searching for modules? I’m also wondering if this search behavior is something that’s built into npm itself or if it’s actually part of the CommonJS specification.
yep, npm does climb up the dir tree to find package.json, so you can use it from diff folders. require() does a similar thing looking for node_modules. super useful for managing your project!
Yes, that’s how npm operates. It starts from your current directory and traverses up the hierarchy searching for a package.json file. This feature is beneficial, especially with nested projects, as you can execute npm commands from subdirectories without having to navigate back to the root. It stops at the first package.json it encounters, which allows for effective handling of nested packages. On the other hand, require() follows a similar path but looks for node_modules folders, starting from the file’s location and moving upwards to find required modules.
This isn’t actually npm-specific - it’s how Node.js’s module resolution works. When you run npm commands, it uses the same upward search that Node.js does internally. It starts in your current directory and walks up through parent directories until it finds a package.json or hits the filesystem root. This isn’t in the CommonJS spec - it’s just how Node.js implements things, and npm inherits that behavior. Heads up though: this can get confusing in monorepos where you’ve got multiple package.json files at different levels, since npm will grab the first one it finds going up the tree.