Rewrite Function#optionize for clarity and to use the built-in `lengt…

…h` property for determing the arity of a function.

src/extensions/misc.js

@@ -26,14 +26,21 @@
  *      logOptions(1,2,3, {hello: "world"}) -> logs 3
 **/
 Function.prototype.optionize = function(){
-  var self = this, argumentNames = self.argumentNames(), optionIndex = argumentNames.length - 1, 
-    method = function(){
-    var args = $A(arguments), options = typeof args.last() == 'object' ? args.pop() : {},
-      prefilledArgs = (optionIndex == 0 ? [] : 
-        ((args.length > 0 ? args : [null]).inGroupsOf(optionIndex).flatten())).concat(options);
-    return self.apply(this, prefilledArgs);
+  var self = this, argumentNames = self.argumentNames(), optionIndex = this.length - 1;
+
+  var method = function() {
+    var args = $A(arguments);
+
+    var options = (typeof args.last() === 'object') ? args.pop() : {};
+    var prefilledArgs = [];
+    if (optionIndex > 0) {
+      prefilledArgs = ((args.length > 0 ? args : [null]).inGroupsOf(
+       optionIndex).flatten()).concat(options);
+    }
+
+    return self.apply(this, prefilledArgs);    
   };
-  method.argumentNames = function(){ return argumentNames };
+  method.argumentNames = function() { return argumentNames; };
   return method;
 };