npm node_modules not being properly nested?

Question

I'm getting unexpected behavior when using npm. For example when installing express with the command:

npm install express

I would expect that a folder named, "express" would be created in the "node_modules" directory and that it's dependencies would be installed within a "node_modules" sub-directory within this folder.

What I am seeing is that the "express" folder is being created but all of it's dependencies are being added to the root "node_modules" directory (same level as express) in my project folder and not nested within the "express" folder.

Why is this happening? (using npm v3.3.5)

Answer 1

It's a design change for npm@3, it deduplicates by default. See:

Flat, flat, flat!

Your dependencies will now be installed maximally flat. Insofar as is possible, all of your dependencies, and their dependencies, and THEIR dependencies will be installed in your project's node_modules folder with no nesting. You'll only see modules nested underneath one another when two (or more) modules have conflicting dependencies.

https://github.com/npm/npm/blob/ff47bc138e877835f1c0f419fea5f5672110678a/CHANGELOG.md#flat-flat-flat

https://github.com/npm/npm/issues/6912