Use of @ symbol in Node module names

问题:

I'm looking at some code from a coworker wrote and she's using the @ symbol in require statements. This is the first line of one of these files:

var restServer = require('@company/config')

When I try to run this code, I get an error:

Error: Cannot find module '@company/config'

Which I frankly expect, there's nothing that looks like this in my directory for require to recognize! It seems like there's some magic going on here, which I hate.

All I can guess is that either this is some obscure npm or Node trick that I haven't been exposed to, or maybe that there's some other dark art of configuration that I'm not getting. Any info appreciated, even if it's just an explanation of how @ works with require.

Other ideas: Chef is involved somewhere in this whole thing, so that might be relevant.

Update: 99% certain this is an issue with the way npm config works at this point, but still unsure of how to go about fixing it.

Update2 based on some stuff I uncovered:

Dereks-MacBook-Pro:project-dir derekjanni$ npm config set //registry.npmjs.org/:authtoken $SECRET_TOKEN

Dereks-MacBook-Pro:project-dir derekjanni$ npm install
npm ERR! Darwin 15.0.0
npm ERR! argv "/usr/local/Cellar/node/5.5.0/bin/node" "/usr/local/bin/npm" "install"
npm ERR! node v5.5.0
npm ERR! npm  v3.5.3
npm ERR! code E404
npm ERR! 404 Not found : @company/config
npm ERR! 404  '@company/config' is not in the npm registry.

回答1:

Scoped packages in npm are preceded by an '@' symbol: https://docs.npmjs.com/misc/scope

The docs include additional information on requiring scoped packages: https://docs.npmjs.com/misc/scope#requiring-scoped-packages

Requiring scoped packages

Because scoped packages are installed into a scope folder, you have to include the name of the scope when requiring them in your code, e.g.

require('@myorg/mypackage')

There is nothing special about the way Node treats scope folders, this is just specifying to require the module mypackage in the folder called @myorg.

回答2:

So I solved this one myself.

Turns out @company/config is one of our private NPM repositories, hosted on npm and defined by this alias to an internal GitHub repository: it had nothing to do with how require works.

Using @ may or may not be a protocol that I was unaware of for private NPM repos, keep that in mind if you run into this.

回答3:

When you call require() it reads a route. Since there seems to be no problem if you name a folder as @company, you should be able to require something with an @.

Your coworker may have wanted to keep @company/config.js for herself because configurations usually are personal and could not be the same for another user.

require will call files inside your project folder, with a detail:

• If you call files inside your project folders you must add ./ in front of your route.
• If you call any global package such as http or any npm modules (which are installed at node_modules), you can omit the ./.

I created a route @company/config inside my test project folder. It only allowed me to require it using ./@company/config. Only when i moved the folder inside node_modules, it allowed me to require('@company/config');.

I wouldn't recommend to put any module inside node_modules, it's just a 'container' for npm packages. Try to create a new config file and change the require route or simply delete the require and create a config object in your main file.

回答4:

Apart from scoped packages, the '@' can arise due to module-alias package in npm. Through module aliasing you can use frequently used modules without requiring its entire path. Also its effective when directory structure is long. e.g.) require('../../../../some/very/deep/module')

Instead you can use: var module = require('@deep/module')

In package.json you can provide the modules for which you are providing alias:

"_moduleAliases": {
  "@root"      : ".", // Application's root
  "@deep"      : "src/some/very/deep/directory/or/file",
  "@my_module" : "lib/some-file.js",
  "something"  : "src/foo", // Or without @. Actually, it could be any string
}

And in the main file of the app use this:

require('module-alias/register');

Refer here for detailed info: module-alias