My attempt at some sort of string builder for a chat thing.

gistfile1.js

// http://stackoverflow.com/questions/5306729/how-do-markov-chain-chatbots-work
// Following this answer to try and make something.

function Chat(dict) {
	var dictionary = dict || {};
	var add_words = function(str, dict) {
		var i = 0;
		var words = str.split(" ");
		var first = words[i++];
		var second = words[i++];
		while (i < words.length) {
			var third = words[i++];
			var key = first + " " + second;
			if (typeof dict[key] == 'undefined') { dict[key] = []; }
			dict[key].push(third);
			first = second;
			second = third;
		}
		return dict;
	};
	var build_string = function(dict, length) {
		var dict_keys = [];
		for (var k in dict) { dict_keys.push(k); }
		var start_key = Math.round(Math.random()*dict_keys.length)%dict_keys.length;
		var key = dict_keys[start_key];
		var str = key;
		while (str.split(" ").length < length) {
			var value_index = Math.round(Math.random()*dict[key].length)%dict[key].length;
			var value = dict[key][value_index];
			str = str + " " + value;
			key = key.split(" ")[1] + " " + value;
			if (typeof dict[key] == 'undefined') { break; }
		}
		return str;
	};
	return {
		add: function(text) {
			return dictionary = add_words(text, dictionary);
		},
		str: function(length) {
			return build_string(dictionary, length);
		}
	}
}