Injector

var injector = {
  storage: {},
  register: function(name, resource) {
    this.storage[name] = resource;
  },
  resolve: function(target) {
    var FN_ARGS = /^function\s*[^\(]*\(\s*([^\)]*)\)/m;
    var STRIP_COMMENTS = /((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg;
    fnText = target.toString().replace(STRIP_COMMENTS, '');
    argDecl = fnText.match(FN_ARGS)[1].split(/, ?/g);
    var args = [];
    for(var i=0; i<argDecl.length; i++) {
      if(this.storage[argDecl[i]]) {
        args.push(this.storage[argDecl[i]]);
      }
    }
    return function() {
      target.apply({}, args);
    }    
  }
};

var dataMockup = ['John', 'Steve', 'David'];
var body = document.querySelector('body');
var ajaxWrapper = {
  get: function(path, cb) {
    console.log(path + ' requested');
    cb(dataMockup);
  }
}

var displayUsers = function(domEl, ajax) {
  ajax.get('/api/users', function(users) {
    var html = '';
    for(var i=0; i < users.length; i++) {
      html += '<p>' + users[i] + '</p>';
    }
    domEl.innerHTML = html;
  });
}


injector.register('domEl', body);
injector.register('ajax', ajaxWrapper);
 
displayUsers = injector.resolve(displayUsers);
displayUsers();