Cannot find module formidable - Node.js

Question

I'm starting to develop with node.j,I meet an issue regarding the using of the module 'formidable'.

I have this error:

Error: Cannot find module 'formidable'

Here is the module list installed using 'npm ls installed' :

├─┬ [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ └── [email protected] 
├── [email protected] 
├─┬ [email protected] 
│ ├── [email protected] 
│ └─┬ [email protected] 
│   ├── [email protected] 
│   ├── [email protected] 
│   └─┬ [email protected] 
│     ├── [email protected] 
│     ├── [email protected] 
│     └── [email protected] 
├─┬ [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├─┬ [email protected] 
│ │ └── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├─┬ [email protected] 
│ │ ├── [email protected] 
│ │ └── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ ├── [email protected] 
│ └── [email protected] 
└─┬ [email protected] 
  ├── [email protected] 
  ├── [email protected] 
  └─┬ [email protected] 
    ├─┬ [email protected] 
    │ └── [email protected] 
    ├── [email protected] 
    ├─┬ [email protected] 
    │ ├── [email protected] 
    │ └── [email protected] 
    └── [email protected] 

I add that it is the only module who generate this error.

Also, I don't really understand the way are encapsulated some module, it appears that npm is installing the module directly in the directory I'm using the module installation command, and I notice that formidable has been installed in the express/connect/ module on its first installation.

Can you give me more information about the module installation tree.
Thank for your replies

Cheers

Solution 1

To understand module resolution, have a look at the Modules documentation, especially Loading from node_modules Folders.

For example, if the file at '/home/ry/projects/foo.js' called require('bar.js'), then node would look in the following locations, in this order:

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

NPM takes advantage of this by installing modules into:

./node_modules/{module}

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

./node_modules/formidable

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

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

You can however install modules as "global," but you have to explicitly ask for it with -g or --global:

npm install -g formidable

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

---

As for the tree output, you current 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 these modules' dependencies, and their dependencies, etc., but only these 5 are available for require(...) within your scripts.

Solution 2

The accepted answer looks very comprehensive and correct, but this worked for me:

npm install -d

d stands for dependencies (I think)

Comments

[Yash]

+1 it helped me C:\Users\yash\AppData\Roaming\npm-cache\selenium-webdriver\2‌​.47.0\package\exampl‌​e ctrl + shift + open command window here then used npm install -d it installed all dependencies then run an example node google_search.js

[Trunk]

Thanks for that! Suddenly, it's added to the project dependencies . . .