Issue #202 ... fallback method for sparse arrays.

test/collections.js

@@ -26,10 +26,6 @@ $(document).ready(function() {
     _.each([1, 2, 3], function(num, index, arr){ if (_.include(arr, num)) answer = true; });
     ok(answer, 'can reference the original collection from inside the iterator');
 
-    answers = [];
-    _.each({range : 1, speed : 2, length : 3}, function(v){ answers.push(v); });
-    ok(answers.join(', '), '1, 2, 3', 'can iterate over objects with numeric length properties');
-
     answers = 0;
     _.each(null, function(){ ++answers; });
     equals(answers, 0, 'handles a null properly');
@@ -185,7 +181,7 @@ $(document).ready(function() {
     people = _.sortBy(people, function(person){ return person.age; });
     equals(_.pluck(people, 'name').join(', '), 'moe, curly', 'stooges sorted by age');
   });
-  
+
   test('collections: groupBy', function() {
     var parity = _.groupBy([1, 2, 3, 4, 5, 6], function(num){ return num % 2; });
     ok('0' in parity && '1' in parity, 'created a group for each value');

underscore.js

@@ -73,7 +73,7 @@
       obj.forEach(iterator, context);
     } else if (_.isNumber(obj.length)) {
       for (var i = 0, l = obj.length; i < l; i++) {
-        if (iterator.call(context, obj[i], i, obj) === breaker) return;
+        if (i in obj && iterator.call(context, obj[i], i, obj) === breaker) return;
       }
     } else {
       for (var key in obj) {
@@ -250,7 +250,7 @@
       return a < b ? -1 : a > b ? 1 : 0;
     }), 'value');
   };
-  
+
   // Groups the object's values by a criterion produced by an iterator
   _.groupBy = function(obj, iterator) {
     var result = {};
@@ -512,7 +512,7 @@
     var funcs = slice.call(arguments);
     return function() {
       var args = slice.call(arguments);
-      for (var i=funcs.length-1; i >= 0; i--) {
+      for (var i = funcs.length - 1; i >= 0; i--) {
         args = [funcs[i].apply(this, args)];
       }
       return args[0];