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npm v3 Dependency Resolution

npm3 resolves dependencies differently than npm2.

While npm2 installs all dependencies in a nested way, npm3 tries to mitigate the deep trees and redundancy that such nesting causes. npm3 attempts this by installing some secondary dependencies (dependencies of dependencies) in a flat way, in the same directory as the primary dependency that requires it.

The key major differences are:

Imagine we have a module, A. A requires B.

A depends on B

Now, let's create an application that requires module A.

On npm install, npm v3 will install both module A and its dependency, module B, inside the /node_modules directory, flat.

In npm v2 this would have happened in a nested way.

npm2 vs 3

Now, let's say we want to require another module, C. C requires B, but at another version than A.

new module dep, C

However, since B v1.0 is already a top-level dep, we cannot install B v2.0 as a top level dependency. npm v3 handles this by defaulting to npm v2 behavior and nesting the new, different, module B version dependency under the module that requires it -- in this case, module C.

nested dep

In the terminal, this looks like this:

tree

You can list the dependencies and still see their relationships using npm ls:

npmls

If you want to just see your primary dependencies, you can use:

npm ls --depth=0

npmlsdepth0

Last modified February 11, 2017           Found a typo? Send a pull request!

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