Poor mans JavaScript dependency injection

ioc.js

(function () {

  (typeof window == 'undefined' ? global : window).ioc = ioc;

  var singletons = {};

  function ioc (Constructor, previous) {

    if ((previous || (previous = [])).indexOf(Constructor) != -1) {
      throw new Error('circular!');
    }
    else {
      previous.push(Constructor);
    }

    var instances = [];
    foreach(dependencyOf(Constructor), function (Dependency) {
      var dependency;
      if (Dependency.length) {
        dependency = ioc(Dependency, previous);
      }
      else {
        dependency = singletons[Dependency.toString()] || new Dependency();
      }
      instances.push(dependency);
    });
    return create(Constructor, instances);
  }

  ioc.singleton = function (Constructor) {
    if (typeof Constructor === 'object') {
      singletons[Constructor.constructor.toString()] = Constructor;
      return;
    }
    singletons[Constructor.toString()] = new Constructor();
  };

  function dependencyOf (Constructor) {
    return map(parametersOf(Constructor.toString()), function (parameter) {
      var DependencyName = capitalize(parameter);
      try {
        var Dependency = eval(DependencyName);
        return Dependency;
      }
      catch (e) {
        throw new Error('No type ' + DependencyName + ' in scope, ' +
                        'which is a dependency of ' + Constructor +
                        '\n' + e);
      }
    });
  }

  var PARAMETERS_REGEX = /\((.*?)\)/;
  function parametersOf (constructorString) {
    var matches = constructorString.match(PARAMETERS_REGEX);
    return matches[1] && matches[1].replace(/ /g, '').split(',') || [];
  }

  function capitalize (string) {
    return string[0].toUpperCase() + string.slice(1);
  }

  function create (Klass, args) {
    function F () {}
    F.prototype = Klass;
    var instance = new F();
    Klass.apply(instance, args);
    return instance;
  }

  function map (array, fn) {
    var result = [];
    foreach(array, function (el) { result.push(fn(el)); });
    return result;
  }

  function foreach (array, fn) {
    for (var i = 0; i < array.length; i++) fn(array[i]);
  }
})();

/* example */

function Service () {
  this.name = 'the service';
}

var i = 0;
function Messages () {
  this.welcome = 'hello from messages #' + i++;
}

/* singleton Messages */
//ioc.singleton(Messages);

/* or, use a specific instance for all Messages */
//var messages = new Messages();
//messages.welcome = 'hello there!';
//ioc.singleton(messages);

function Controller (messages, service) {
  this.service = service;
  this.messages = messages;
}

function AnotherController (messages, service) {
  this.service = service;
  this.messages = messages;
}

console.log(ioc(Controller));
console.log(ioc(AnotherController));