Refactor to Strategy in Javascript

refactor_to_strategy.js

var message = require('./lib/zmessage');

var Strategy = function(f) {
  this.send = f;
};

Strategy.prototype.execute = function(m) {
  this.send(m);
};

var A = new Strategy(function(m) {
  console.log('Type found, take action on message type A');
  message.A.inspect(m);
});


module.exports = {
  switchStrategy: function(strategy) {
    this.strategy = strategy;
  },

  invokeStrategy: function(m) {
    this.strategy.execute(m);
  },
};

msg = message.A.create();
myapp = module.exports;

myapp.switchStrategy(A);
myapp.invokeStrategy(msg);
myapp.switchStrategy(Z); // Not defined error

zmessage.js

module.exports = {

  A: {
    name: 'Message Type A',
    create: function() {
      return ({type: 'A',messages: []});
    },
    inspect: function(m) {
      var out = 'type: A | messages: [m.messages]';
      out = (m.messages.length < 1)?
        out.replace('[m.messages]','empty list'):
        out.replace('[m.messages]',m.messages);
      console.log(out);
    },
  },
  B: {
    name: 'Message Type B',
    create: function() {
      return ({type: 'B',header: {},data: {}});
    },
    inspect: function(m) {
      var out = 'type: B | messages: [m.messages]';
      out = (m.messages.length < 1)?
        out.replace('[m.messages]','empty list'):
        out.replace('[m.messages]',m.messages);
      console.log(out);
    },
  },
}