bundler.js

// common code for implementing require()/exports
var dependencies = {} // loaded modules
var modules = {} // code of your dependencies
// require function
var require = function (module) {
 if (!dependencies[module]) {
   // module not loaded, let’s load it
   var exports = {}
   modules[module](exports)
   // now in `exports` we have the things made “public”
   dependencies[module] = exports
 }
 return dependencies[module]
}
// dependendencies
modules['jquery'] = function (exports) {
  // code of jquery
}
modules['foo'] = function (exports) {
  // code of bar.js
  exports.helloWorld = function () {
    console.log('hello world')
  }
}
modules['bar'] = function (exports) {
  // code of bar.js
}
// etc…
// here goes the code of your "entry file".
// Which is the entry point of your code
// For example:
var $ = require('jquery')
var foo = require('foo')
var bar = require('bar')
foo.helloWorld()