Add in basic multiply functionality.

mathstuff.js

@@ -8,4 +8,13 @@
     });
     return value;
   };
+
+  $.fn.multiply = function(){
+    if (this.length == 0) return 0;
+    var value = 1;
+    this.each(function(){
+      value = value * $(this).val();
+    });
+    return value;
+  };
 })( jQuery );

mathstuff.tests.html

@@ -62,6 +62,26 @@
         var value = $('.two').sum();
         equal(value, 1.3, "should return 1.3");
       });
+
+    module("Multiply");
+
+      test("returns 0 when given no items", function(){
+        var value = $('input[name=nothing]').multiply();
+        equal(value, 0, "should return zero" );
+      });
+
+      test("returns 1 when given one item of value 1", function(){
+        $('input[name=one]').val(1);
+        var value = $('input[name=one]').multiply();
+        equal(value, 1, "should return one" );
+      });
+
+      test("returns 6 when given two items that multiply to 6", function(){
+        $('#B1').val(2);
+        $('#B2').val(3);
+        var value = $('.two').multiply();
+        equal(value, 6, "should return six" );
+      });
   });
   </script>