Functions part2(Chapter 4 of JavaScript: The Good Parts)

 1 var serial_maker = function () {

 2                 var prefix = '';

 3                 var seq = 0;

 4 

 5                 return {

 6                     set_prefix: function (p) {

 7                         prefix = String(p);

 8                     },

 9 

                     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();

             alert(unique);

 

 

 1 var fibonacci = function (  ) {
 2     var memo = [0, 1];
 3     var fib = function (n) {
 4         var result = memo[n];
 5         if (typeof result !== 'number') {
 6             result = fib(n - 1) + fib(n - 2);
 7             memo[n] = result;
 8         }
 9         return result;
10     };
11     return fib;
12 }(  );
13 
14 
15 var fibonacci = memoizer([0, 1], function (shell, n) {
16     return shell(n - 1) + shell(n - 2);
17 });
18 
19 var factorial = memoizer([1, 1], function (shell, n) {
20     return n * shell(n - 1);
21 });