Unable to find a formidable module - Node.js

Question

I'm starting to develop using node.j, I come across a question about using the formidable module.

I have this error:

Error: cannot find the formidable module

Here is the list of modules installed with "npm ls installed":

 ├─┬ express@2.5.9 │ ├── connect@1.8.7 │ ├── mime@1.2.4 │ ├── mkdirp@0.3.0 │ └── qs@0.4.2 ├── formidable@1.0.9 ├─┬ node-inspector@0.1.10 │ ├── paperboy@0.0.3 │ └─┬ socket.io@0.8.7 │ ├── policyfile@0.0.4 │ ├── redis@0.6.7 │ └─┬ socket.io-client@0.8.7 │ ├── uglify-js@1.0.6 │ ├── websocket-client@1.0.0 │ └── xmlhttprequest@1.2.2 ├─┬ npm@1.1.21 │ ├── abbrev@1.0.3 │ ├── archy@0.0.2 │ ├── block-stream@0.0.5 │ ├ ── chownr@0.0.1 │ ├── fstream@0.1.18 │ ├─┬ fstream-npm@0.0.6 │ │ └── fstream-ignore@0.0.5 │ ├── graceful-fs@1.1.8 │ ├── inherits@1.0.0 │ ├─ ─ ini@1.0.2 │ ├── lru-cache@1.0.5 │ ├── minimatch@0.2.2 │ ├── mkdirp@0.3.0 │ ├─┬ node-gyp@0.4.1 │ │ ├── ansi@0.0.4 │ │ └─  glob@3.1.9 │ ├── node-uuid@1.3.3 │ ├── nopt@1.0.10 │ ├── proto-list@1.0.0 │ ├── read@0.0.2 │ ├── request@2.9.153 │ ├── rimraf@2.0.1 │ ├── semver@1.0.13 │ ├── slide@1.1.3 │ ├── tar@0.1.13 │ ├── uid-number@0.0.3 │ └── which@1.0.5 └─┬ socket.io@0.9.6 ├ ── policyfile@0.0.4 ├── redis@0.6.7 └─┬ socket.io-client@0.9.6 ├─┬ active-x-obfuscator@0.0.1 │ └── zeparser@0.0.5 ├── uglify-js@1.2.5 ├─┬ ws@0.4.14 │ ├── commander@0.5.2 │ └── options@0.0.3 └── xmlhttprequest@1.2.2 

I add that this is the only module that generates this error.

In addition, I really don’t understand how any module is encapsulated, it seems that npm installs the module directly in the directory in which I use the module installation command, and I notice that the formidable was installed in express / connect / module during the first installation .

Can you give me more information about the module installation tree.
thank you for your responses

Greetings

Answer 1

To understand module resolution, see Module Documentation , especially Downloading from the node_modules Folders .

For example, if the file in '/home/ry/projects/foo.js' is called require('bar.js') , then the node will look in the following places in the following order:

• /home/ry/projects/node_modules/bar.js
• /home/ry/node_modules/bar.js
• /home/node_modules/bar.js
• /node_modules/bar.js

NPM uses this by installing modules in:

 ./node_modules/{module} 

So, when you use npm install formidable , it will create and install the module in:

 ./node_modules/formidable 

But this means that only scripts in the current directory, including subdirectories, will succeed in using require('formidable') :

 ./foo.js ./lib/bar.js ./src/baz.js ./src/sub/qux.js 

However, you can install modules as "global", but you must explicitly request it with -g or --global :

 npm install -g formidable 

Then any script on the system must be able to require('formidable') .

---

As for tree output, you have 5 installed modules available from the current directory:

• express
• formidable
• node-inspector
• npm
• socket.io

Everything else in the tree is a list of the dependencies of these modules, their dependencies, etc., but only these 5 are available for require(...) inside your scripts.

Answer 2

The accepted answer seems very comprehensive and correct, but it worked for me:

 npm install -d 

d means dependencies (I think)