node cannot find express module?

Question

I am unaware what is causing this problem, because I thought it should be working. I do have expressed installed, at least according to npm:

C:\Users\phucker\Desktop>node init.js

module.js:340
    throw err;
          ^
Error: Cannot find module 'express'
    at Function.Module._resolveFilename (module.js:338:15)
    at Function.Module._load (module.js:280:25)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at Object.<anonymous> (C:\Users\phucker\Desktop\init.js:1:77)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)

C:\Users\phucker\Desktop>npm express -v
1.3.2

C:\Users\phucker\Desktop>

the code contained in init.js is

var express = require('express');
var app = express();

app.get('/', function(req, res){
  res.send('hello world');
});

app.listen(3000);

Solution 1

You need to have express installed locally in your node_modules folder. Check your node_modules and install it again if it is not there

Solution 2

npm express -v doesn't show the version of Express that you have installed, it shows the version of npm.

To show which version of Express you have installed, try this:

npm ls express

Solution 3

Maybe it is not your problem, but it is often confusing distinction between global and local installations for beginners. If you use require('module_name') in your code, each module must be installed locally using npm install module_name or using dependencies in package.json.

Global installation is only for running commands like express my_new_project.

You can list all installed local modules for actual directory using npm list and all global ones runningnpm list -g.

Solution 4

Please check the following if you have installed express globally

i.e using the command npm install -g express

1. Check if express module is imported in your code using

   var express = require('express')

2. On windows check if the path C:\Users\<user_name>\AppData\Roaming\npm is on the PATH environment variable

For installations that do not have express installed globally

1. Navigate to you folder C:\node project
2. Do a local installation of Express using npm install express
3. Import express module in your code using var express = require('express')

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Comments

[Admin]

Why? What is the point of being able to install something globally if it can't be used "globally"?

[Akshat Jiwan Sharma]

@Sosukodo a very good explanation for this is on the npm blog global installations are good if you want to use the executable from your shell. For using them as a library in your program it is preferable to install them locally. Though you can create symbolic links from global installations as well.