Javascript Module Pattern

jsmodule.js

<script type="text/javascript">
		//from book 'Javascript the Good parts' p.58
			//The methods do not make use of this or that. 
			//As a result, there is no way to com- promise the seqer. 
			//It isn’t possible to get or change the prefix or seq 
			//except as per- mitted by the methods. The seqer object 
			//is mutable, so the methods could be replaced, but 
			//that still does not give access to its secrets. 
			//seqer is simply a collection of functions, and 
			//those functions are capabilities that grant specific 
			//powers to use or modify the secret state.
			var serial_maker = function(){
				var prefix = '';
				var seq = 0;
				
				return {
					set_prefix: function (p) {
					  prefix = String(p);
					},
					set_seq: function (s) {
					  seq = s;
					},
					gensym: function () {
					  var result = prefix + seq;
					  seq += 1;
					  return result;
					}
				};
			};
			
			var seqer = serial_maker();
			seqer.set_prefix('Q');
			seqer.set_seq(1000);
			var unique = seqer.gensym();
			console.log(unique);
		</script>