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app-module-path

Simple module to add additional directories to the Node module search for top-level app modules

app-module-path

This simple module enables you to add additional directories to the Node.js module search path (for top-level app modules only). This allows application-level modules to be required as if they were installed into the node_modules directory.

npm install app-module-path --save

// ***IMPORTANT**: The following line should be added to the very 
//                 beginning of your main script! 
require('app-module-path').addPath(baseDir);

IMPORTANT: The search path should be modified before any modules are loaded!

Example:

In your my-app/index.js (or my-app/server.js) file:

// Add the root project directory to the app module search path: 
require('app-module-path').addPath(__dirname);

Given the following example directory structure:

  • my-app/
    • src/ - Source code and application modules directory
      • foo/ - A module directory
        • index.js
      • bar/ - Another module directory
        • index.js
    • node_modules/ - Installed modules
      • installed-baz/ - An installed module
        • index.js
    • index.js - Main script

The following will work for any modules under the src directory:

// All of the following lines will work in "src/foo/index.js" and "src/bar/index.js": 
var foo = require('src/foo'); // Works 
var bar = require('src/bar'); // Works 
var baz = require('installed-baz'); // Works 

Lastly, by design, installed modules (i.e. modules under the node_modules directory) will not be able to require application-level modules so the following will not work:

// All of the following lines will *not* work in "node_modules/installed-baz/index.js"! 
var foo = require('src/foo'); // Fails 
var bar = require('src/bar'); // Fails 

This module supports an alternate method of adding a path to the Node.js module search path that requires less code. Requiring or importing the app-module-path/register module will result in the directory of the calling module being added to the Node.js module search path as shown below:

require('app-module-path/register');
 
// Is equivalent to: 
require('app-module-path').addPath(__dirname);
import "app-module-path/register";
 
// Is equivalent to: 
import { addPath } from 'app-module-path';
addPath(__dirname);

Additionally, requiring or importing app-module-path/cwd will result in the current working directory of the Node.js process being added to the module search path as shown below:

require('app-module-path/cwd');
 
// Is equivalent to: 
require('app-module-path').addPath(process.cwd());
import "app-module-path/cwd";
 
// Is equivalent to: 
import { addPath } from 'app-module-path';
addPath(process.cwd());
  • Search path order:
    • App module paths will be added to the beginning of the default module search path. That is, if a module with the same name exists in both a node_modules directory and an application module directory then the module in the appliation module directory will be loaded since it is found first.
  • Node.js compatibility:
    • This module depends on overriding/wrapping a built-in Node.js method, and it is possible (but unlikely) that this behavior could be broken in a future release of Node.js (at which point a workaround would need to be used)
    • This module will not change or break modules installed into the node_modules directory.
  • Recommendations:
    • Since this module changes the Node.js convention of how non-relative modules are resolved, it is recommended (but not required) to put all app modules in a common directory below the application root (such as my-app/src or my-app/app_modules) and then to add the application root to the search path. The require calls would then be something like require('src/foo') or require('app_modules/foo'). The common prefix makes it more clear that the module can be found in the application's modules directory and not in the node_modules directory.

Pull requests, bug reports and feature requests welcome.

BSD-2-Clause