in node.js, how does one file in a module see functions in another file in the module?

Question

in node.js, how does one file in a module see functions in another file in the module?

in a module containing two files in ./modx: modx.js and helper.js:

./modx/package.json:

{ "name" : "module x",
  "main" : "./modx.js" }

./modx/helper.js:

function subFunc() { }

./modx/modx.js:

exports.mainFunc = function() {
   var x = subFunc();
}

how do I make subFunc() in helper.js visible to modx.js when both are in the modx module?

javascript
node.js
module

Answer 1

Inside ./modx/helper.js

var subFunc = function subFunc() {}
exports.subFunc = subFunc;

Inside .modx/modx.js

var helper = require('./helper.js');
exports.mainFunc() {
    var x = helper.subFunc();
}

The result here is that the subFunc function in helper.js is externally available and the mainFunc in modx.js is externally available.

Answer 2

The only object in script A visible from script B is module.exports. Adding objects/functions to module.exports (just like you did it with mainFunc) makes them visible from the outside. There is no other way.