Many unknown modules in node_modules folder

Question

I am new to nodejs. And I found that there are many unknown modules in node_modules folder after I installed three modules (express, jade, gulp) in my local project.

Unknown module examples in the node_modules:

• vary
• statuses
• send
• promise

From the tutorials I see from others, after they installed gulp, there will be only one "gulp" folder in their node_modules folder, but this is not my case. Why? Thank you.

Answer 1

The node package manager ( npm ) updated recently, as part of that update, all modules are installed in the top level node_modules folder. This includes modules that your dependencies need to install. In the past these modules would be nested inside another node_modules folder in express (for example).

This is why the tutorials you read say different, likely they were written before this update.

It is mentioned in the npm changelog here

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.

#3697 This will hopefully eliminate most cases where windows users ended up with paths that were too long for Explorer and other standard tools to deal with.

#6912 (#4761 #4037) This also means that your installs will be deduped from the start.

#5827 This deduping even extends to git deps.

#6936 (#5698) Various commands are dedupe aware now. This has some implications for the behavior of other commands:

npm uninstall removes any dependencies of the module that you specified that aren't required by any other module. Previously, it would only remove those that happened to be installed under it, resulting in left over cruft if you'd ever deduped. npm ls now shows you your dependency tree organized around what requires what, rather than where those modules are on disk.

#6937 npm dedupe now flattens the tree in addition to deduping. And bundling of dependencies when packing or publishing changes too:

#2442 bundledDependencies no longer requires that you specify deduped sub deps. npm can now see that a dependency is required by something bundled and automatically include it. To put that another way, bundledDependencies should ONLY include things that you included in dependencies, optionalDependencies or devDependencies.

#5437 When bundling a dependency that's both a devDependency and the child of a regular dependency, npm bundles the child dependency. As a demonstration of our confidence in our own work, npm's own dependencies are now flattened, deduped, and bundled in the npm@3 style. This means that npm@3 can't be packed or published by npm@2, which is something to be aware of if you're hacking on npm.