composition.js

Array.prototype.shuffle = function (){
    var i = this.length, j, temp;
    if ( i === 0 ) return;
    while ( --i ) {
        j = Math.floor( Math.random() * ( i + 1 ) );
        temp = this[i];
        this[i] = this[j];
        this[j] = temp;
    }
    return this;
};

var houseFactory = (function () {
  'use strict';
  var thisFormatter;
  var data = [
    'the horse and the hound and the horn that belonged to',
    'the farmer sowing his corn that kept',
    'the rooster that crowed in the morn that woke',
    'the priest all shaven and shorn that married',
    'the man all tattered and torn that kissed',
    'the maiden all forlorn that milked',
    'the cow with the crumpled horn that tossed',
    'the dog that worried',
    'the cat that killed',
    'the rat that ate',
    'the malt that lay in',
    'the house that Jack built',
  ];
  return {
    init: function (orderer, formatter) {
      thisFormatter = formatter;
      data = orderer.order(data);
      return this;
    },
    phrase: function (number) {
      return this.parts(number).join(' ');
    },
    parts: function (number) {
      var self = this;
      return thisFormatter.format(data.slice(Math.max((data.length-1) - number, 0)));
    },
    recite: function () {
      var self = this;
      return data.map(function (element, index) {
        return self.line(index);
      }).join("\n");
    },
    line: function (number) {
      return 'This is ' + this.phrase(number) + ".\n";
    }
  };
}());

var defaultOrderer = {
  order: function (data) {
    return data;
  }
};
var randomOrderer = {
  order: function (data) {
    return data.shuffle();
  }
};

var defaultFormatter = {
  format: function (parts) {
    return parts;
  }
};

var echoFormatter = {
  format: function (parts) {
    return parts
    .map(function(element) { return [element,element];})
    .reduce(function (a,b) { return a.concat(b); });
  }
};

//var house = houseFactory.init(defaultOrderer, defaultFormatter);
//console.log(house.recite());

//var randomHouse = houseFactory.init(randomOrderer, defaultFormatter);
//console.log(randomHouse.recite());

//var echoHouse = houseFactory.init(defaultOrderer, echoFormatter);
//console.log(echoHouse.recite());

var randomEchoHouse = houseFactory.init(randomOrderer, echoFormatter);
console.log(randomEchoHouse.recite());