Question

I wrote a simple application using node. It depends on express, mongodb and mongoose (easy).
So, I created a file called package.json and put this in it:

{
  "name": "booking-dojo",
  "description": "Booking dojo app",
  "version": "0.0.1",
  "private": true,
  "dependencies": {
    "express": "3.x",
    "mongodb": "*",
    "mongoose": "*"
  }
}

I then ran npm install, expecting npm to install those modules and their dependencies.
The result was disappointing:

booking-dojo@0.0.1 /home/merc/Synced/Development/Bookings/app/server
├─┬ express@3.0.0rc3 
│ ├── commander@0.6.1 
│ ├─┬ connect@2.4.3 
│ │ ├── bytes@0.1.0 
│ │ ├── formidable@1.0.11 
│ │ ├── pause@0.0.1 
│ │ └── qs@0.4.2 
│ ├── cookie@0.0.4 
│ ├── crc@0.2.0 
│ ├── debug@0.7.0 
│ ├── fresh@0.1.0 
│ ├── methods@0.0.1 
│ ├── mkdirp@0.3.3 
│ ├── range-parser@0.0.4 
│ └─┬ send@0.0.3 
│   └── mime@1.2.6 
├─┬ mongodb@1.1.4 
│ └── bson@0.1.1 
└─┬ mongoose@3.0.3 
  ├── hooks@0.2.1 
  └── ms@0.1.0 

I am confused by this, as I know that express needs jade (and much more), and mongoose needs mongodb.
If I go into node_modules/jade and run npm install, the result from the main tree is very different:

booking-dojo@0.0.1 /home/merc/Synced/Development/Bookings/app/server
├─┬ express@3.0.0rc3 
│ ├── commander@0.6.1 
│ ├─┬ connect@2.4.3 
│ │ ├── bytes@0.1.0 
│ │ ├── formidable@1.0.11 
│ │ ├── pause@0.0.1 
│ │ └── qs@0.4.2 
│ ├─┬ connect-redis@1.4.1 
│ │ └─┬ redis@0.7.2 
│ │   └── hiredis@0.1.14 
│ ├── cookie@0.0.4 
│ ├── crc@0.2.0 
│ ├── debug@0.7.0 
│ ├── ejs@0.8.2 
│ ├── fresh@0.1.0 
│ ├── github-flavored-markdown@1.0.1 
│ ├─┬ hjs@0.0.4 
│ │ └── hogan.js@2.0.0 
│ ├─┬ jade@0.27.2 
│ │ └── mkdirp@0.3.0 
│ ├── methods@0.0.1 
│ ├── mkdirp@0.3.3 
│ ├─┬ mocha@1.4.0
│ │ ├── diff@1.0.2 
│ │ ├── growl@1.5.1 
│ │ └─┬ jade@0.26.3 
│ │   └── mkdirp@0.3.0 
│ ├── range-parser@0.0.4 
│ ├─┬ send@0.0.3 
│ │ └── mime@1.2.6 
│ ├── should@1.1.0 
│ ├─┬ stylus@0.29.0 
│ │ └── cssom@0.2.5 
│ └─┬ supertest@0.0.1 
│   └─┬ superagent@0.5.0 
│     ├── emitter-component@0.0.1 
│     ├── formidable@1.0.9 
│     ├── mime@1.2.5 
│     └── qs@0.4.2 
├─┬ mongodb@1.1.4 
│ └── bson@0.1.1 
└─┬ mongoose@3.0.3 
  ├── hooks@0.2.1 
  └── ms@0.1.0 

So, express has grown a lot. It looks like npm install is only loading some of the dependencies of the sub-modules.

Can somebody please shed some light on this? Why are some dependencies missing? Am I doing something wrong? (likely)

Thanks!

Merc.

Answer 1

The answer was provided by Brandon in a comment to another answer:

“Another thing to note is that if a package depends on a module that can be resolved further up in the dependency chain, it will. For example, since you have mongodb in your package.json, Mongoose doesn’t need to install its own mongodb. – Brandon Tilley 2 days ago

Thank you Brandon! (And this is the answer…)