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' : ``` ├─┬ 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.…

Accepted Answer

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.

Cannot find module formidable - Node.js

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