elaborate underscore initialization so that it works seamlessly on CommonJS, as well as in the browser

test/collections.js

@@ -12,9 +12,13 @@ $(document).ready(function() {
     equals(answer, 2, 'the loop broke in the middle');
     
     var answers = [];
-    _.each([1, 2, 3], function(num) { answers.push(num * this.multiplier);}, {multiplier : 5});
+    _.each([1, 2, 3], function(num){ answers.push(num * this.multiplier);}, {multiplier : 5});
     equals(answers.join(', '), '5, 10, 15', 'context object property accessed');
     
+    answers = [];
+    _.each("moe", function(letter){ answers.push(letter); });
+    equals(answers.join(', '), 'm, o, e', 'iterates over the letters in strings');
+    
     answers = [];
     _.forEach([1, 2, 3], function(num){ answers.push(num); });
     equals(answers.join(', '), '1, 2, 3', 'aliased as "forEach"');

underscore.js

@@ -8,15 +8,25 @@
 
 (function() {
   
-  var root = (typeof window != 'undefined') ? window : exports;
+  /*------------------------- Baseline setup ---------------------------------*/
   
-  var previousUnderscore = root._;
+  // Are we running in CommonJS or in the browser?
+  var commonJS = (typeof window === 'undefined' && typeof exports !== 'undefined');
   
+  // Save the previous value of the "_" variable.
+  var previousUnderscore = commonJS ? null : window._;
+  
+  // Keep the identity function around for default iterators.
   var identity = function(value) { return value; };
-    
-  var _ = root._ = {};
   
-  _.VERSION = '0.2.0';
+  // Create a safe reference to the Underscore object for the functions below.
+  var _ = {};
+  
+  // Export the Underscore object for CommonJS, assign it globally otherwise.
+  commonJS ? _ = exports : window._ = _;
+  
+  // Current version.
+  _.VERSION = '0.2.1';
       
   /*------------------------ Collection Functions: ---------------------------*/
     
@@ -417,7 +427,7 @@
   // Run Underscore.js in noConflict mode, returning the '_' variable to its
   // previous owner. Returns a reference to the Underscore object.
   _.noConflict = function() {
-    root._ = previousUnderscore;
+    if (!commonJS) window._ = previousUnderscore;
     return this;
   };
   
@@ -452,10 +462,6 @@
   _.inject   = _.reduce;
   _.filter   = _.select;
   _.every    = _.all;
-  _.some     = _.any;
-  
-  /*------------------------- Export for ServerJS ----------------------------*/
-  
-  if (typeof exports != 'undefined') exports = _;
+  _.some     = _.any;  
 
 })();