How to Require Absolute Paths in Node.js

About how to load modules with absolute paths in Node.js. In Node.js, you can load modules and external files with relative paths, but you need a little ingenuity to load them with absolute paths.

Until recently, I was requiring external modules in a format like the following. It seemed to be working well. However.

var noderc = require( path.relative( __dirname , process.env.NODE_RC_FILE ) );

Actually, the above code is incomplete and causes an error when the reference path is in the same level directory.

module.js:550
    throw err;
    ^

Error: Cannot find module 'noderc.js'
    at Function.Module._resolveFilename (module.js:548:15)
    at Function.Module._load (module.js:475:25)
    at Module.require (module.js:597:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/mnt/c/pg/node/tmp.js:10:14)
    at Module._compile (module.js:653:30)
    at Object.Module._extensions..js (module.js:664:10)
    at Module.load (module.js:566:32)
    at tryModuleLoad (module.js:506:12)
    at Function.Module._load (module.js:498:3)

Why? When there’s a reference path in the same level, it returns a value as a path like noderc.js rather than a path like ./noderc.js.

To put it clearly, it’s like this:

var noderc = require( "noderc.js" ); # => ERROR
var noderc = require( "../node/noderc.js" ); # => OK
var noderc = require( "./noderc.js" ); # => OK

So I wrote the following. When the path is something like “noderc.js”, it converts it to ”./noderc.js”.

global.require_absolute = function( filepath ){

    if ( ! /^\./.test( path.relative( __dirname , filepath ) ) ){
        global.noderc = require( `./${ path.relative( __dirname , filepath ) }` );
    } else {
        global.noderc = require( path.relative( __dirname , filepath ) );
    }

}

And usage example:

require_absolute( "/mnt/c/pg/node/noderc.js" ) ;

require_absolute( process.env.NODE_RC_FILE ) ;

There seems to be deep discussion about Node.js require. This topic alone has 2000 stars.

Better local require() paths for Node.js

Update

Sorry, I was mistaken. The following is more versatile:

global.to_relative = function( filepath ){

    if ( ! /^\./.test( path.relative( __dirname , filepath ) ) ){
        return `./${ path.relative( __dirname , filepath ) }` ;
    } else {
        return path.relative( __dirname , filepath ) ;
    }

}

var noderc = require( to_relative( process.env.NODE_RC_FILE ) ) ;