Node modules that instantiate things?

Question

Node modules that instantiate things?

Can I build a module that exports instantiated variables?

Module:

var module1 = require('module1')
var Module2 = require('module2')

module1.dosomething(variables)
exports.module1 = module1

//or

module2 = new Modle2(variables)
module2.dosomething(variables)
exports.module2 = module2

Can I require the module above in many other files and use the exports as instantiated variables or will they be re-instantiated every time I require them and not shared between the files requiring them.

Thanks!

javascript
node.js
variables

Answer 1

Your example is confusing because you use module1 in multiple contexts, both as a module, a variable within another module, and an exported property of that module.

Think of modules as closures and exports as return values. Most likely you want to export a function/factory function and call that every time if you want to create new instances with the export, anything else will be shared since it just returns the object.

Module1

module.exports.var1 = function(opts) {
    // do stuff
    return variables;
};

module.exports.var2 = new Blah(); // single instance

Other module

var var1 = require('module1').var1({ opt1: 'foo' }); // New instance every time
var var2 = require('module1').var2; // Same var instance even if you include in another module

Answer 2

You can even do things like this to be really annoying. Most npm modules make you create instantiated versions to avoid this kind of silliness.

// file.js
var m1 = require('./m1');
m1.awesome = false;
console.log("I am awesome", m1.awesome);

// file2.js
var m1 = require('./m1');
console.log("I am awesome", m1.awesome);

// both.js
require('./file');
require('./file2');

// m1.js
exports.awesome = true;

now run this:

node file1.js
I am awesome false

node file2.js
I am awesome true

node both.js
I am awesome false
I am awesome false