Express module not found when installed with NPM

问题:

When I try to run the app.js file created by express, I get the following error:

$ node app.js

node.js:134
        throw e; // process.nextTick error, or 'error' event on first tick
        ^
Error: Cannot find module 'express'
    at Function._resolveFilename (module.js:320:11)

When I type in 'express --version' I get a return statement of 2.3.3. I used npm to install express. I had to manually make npm using these instructions:

git clone http://github.com/isaacs/npm.git
cd npm
sudo make install

The error is Error: Cannot find module 'express'.

Do I need to do something after installing npm and express in order to make express see the modules created by npm?

My node is version: 0.4.6 My express is version: 2.3.3 My npm is version: 1.0.6

Express is installed globally. I used the -g flag to install it.

Edit: When I try "node -e require.paths" I get:

[ '/home/user/.node_modules', '/home/user/.node_libraries', '/usr/local/lib/node' ]

So, node isn't detecting the npm installation. How do I get node to detect the npm installation?

回答1:

I had the same problem. This worked for me though:

Seems like npm (now?) installs node modules to /usr/local/lib/node_modules/ and not /usr/local/lib/node/

What I did was simply to copy everything from node_modules to node: sudo cp -r /usr/local/lib/node_modules/* usr/local/lib/node/ and now it seems to be working for me.

Hope this helps you :-)

回答2:

• Install express

  npm install -g express

• Create a new app

  express your_app

• cd into app directory

  cd your_app

• use npm link to resolve modules

  npm link express

回答3:

Use local installs for require(), and global installs for command-line apps.

If you need both, use the npm link command.

回答4:

On Ubuntu 12.04 you have to add the export NODE_PATH=/usr/local/lib/node_modules to your /.bashrc to use globally installed modules.

回答5:

It appears that while npm had been updated to install global modules into /usr/local/lib/node_modules, Node's own require.paths does not yet reflect this change.

There are two reasonable solutions:

1. Add the following code to the top of your application:

require.paths.push('/usr/local/lib/node_modules');

Pro: non-invasive, easy to add

Con: requires discipline, future versions of node will restrict access to require.paths

2. As root, execute:

ln -s /usr/local/lib/node_modules /usr/local/lib/node

Pro: reasonably non-invasive

Con: requires root, modifies linux fs, might not survive system updates

回答6:

What about NODE_PATH=/usr/local/lib/node_modules in .bashrc or .bash_profile? I think it's the real correct way.

回答7:

It may happen, if you're using windows, that the environment variable NODE_PATH is not set, and thus when you execute node fileName.js it won't find the libraries. Check for the variable on your console, and if not present, create it. Give it the NODE_HOME\node_modules value, where NODE_HOME is your node install dir. This path is where npm install puts every module upon downloading.

回答8:

Set NODE_PATH=NODE_HOME\node_modules.

I'm using windows 7 and it works fine.

回答9:

require.paths is removed, use the NODE_PATH environment variable instead.

回答10:

It looks like the easiest way to do this is to run npm install from your app's folder. This tells npm to hook everything up.

It's the last instruction after express <appname>:

...
dont forget to install dependencies:
$ cd <appname> && npm install

回答11:

for all problems with express with a mac computer:

The solution is:

1.- chown to your user the .npm folder :

sudo chown -R Webmaste /Users/webmaste/.npm/

1. At your test folder or your folder:

sudo npm install -g express@2.5.8

1. Invoke express from your actual location:

/usr/local/share/npm/bin/express

4: sudo cd . && npm install

5: finally:

node app

---

the final message in the console should look like this:

Express server listening on port 3000 in development mode

回答12:

for mac users

cd /usr/local/lib/node
sudo ln -s ../node_modules/* ./$1

回答13:

I installed gulp and when I ran this gulp command in the command line I got a gulp: command not found error. It appeared that it installed gulp in my local folder that is /home/YOURUSERNAME/.node/lib/node_modules and not in the global npm folder.

You can check npm root folder by running this command: npm root -g, which was returning my personal directory /home/YOURUSERNAME/.node/lib/node_modules and not the expected /usr/local/lib/node_modules.

You can fix this by running npm config set prefix /usr/local command.

回答14:

Finally with Linux a good way to do is to use the command : sudo apt-get install node-express

But with express 4 we must use express-generator to make app skeleton, install it with 'npm install express-generator -g', and then run 'express myapp' command. see also install express