The problem

Usually module availability could be checked using native require method.

const isExists = false;

try {
  require.resolve('angular')
  isExists = true;
} catch (e) {
    
}

But here is problem: I don't want to write try catch statements :)

OK. The real problem appears when developing component with auto requiring modules. require and require.resolve will work correctly until component is in local node_modules. After npm link (that is very useful while developing npm packages) or if components is installed as global package - require and require.resolve will work from global context (at *nix systems /usr/local/lib/node_modules).

For example: I am developing build / server like webpack. And there are loaders (babel-loader, html-loader, json-loader etc). And I want my builder to require loader automatically when it is needed. So my node_modules should be as below:

/my-work-directory/node_modules
                         |-builder/
                         |-babel-loader/
                         |-html-loader/
                         |-json-loader/
     

In this case if I run require('babe-loader') at builder component - it will work. But If I npm link my build (for better developing process) or make in global - my node_modules will be as below:

/usr/local/lib/node_modules
                        |-builder/
    

/my-work-directory/node_modules
                         |-(linked directory) builder/
                         |-babel-loader/
                         |-html-loader/
                         |-json-loader/

And in this case if I run require('babe-loader') at builder - will be exception Error: Cannot find module 'babel-loader'. This happens because require depends on __dirname that equals /usr/local/lib/node_modules/builder at builder component. Here is documentation how modules are loading from node_modules folder

Solution

npm install --save magic-require

First resolve modules according to caller module __dirname and if not resolved - try to resolve according to current process.cwd(). 100% supports package.json if loads module as directory.

Examples

import magic from 'magic-require';


magic.isExists('babel-loader'); // true
magic.isExists('expose-loader'); // false

magic.resolve('babel-loader'); // ../../../.. /my-work-directory/node_modules/babe-loader/index.js

const BabelLoader = magic('babel-laoder');

Available methods

• isExists(module) - returns true if module exists and false - if not.
• resolve(module) - returns relative path to requested module from current executing module's __dirname or null.

Community

You are always welcome for ideas and pull requests :)