Add _.chunk to Array functions.

fix _.chunk function

fix _.chunk function

Do not return original array if chunkin in more then array size parts

Do not return original array if chunkin in more then array size parts

spaces clean up

Author: Petr Archakov

test/arrays.js

@@ -538,5 +538,19 @@
     deepEqual(_.range(12, 7, -2), [12, 10, 8], 'range with three arguments a & b & c, a > b, c < 0 generates an array of elements a,a-c,a-2c and ends with the number not less than b');
     deepEqual(_.range(0, -10, -1), [0, -1, -2, -3, -4, -5, -6, -7, -8, -9], 'final example in the Python docs');
   });
-
+  
+  test('chunk', function() {
+    deepEqual(_.chunk([], 2), [], 'chunk for empty array returns an empty array');
+    deepEqual(_.chunk(null, 2), [], 'chunk for null returns an empty array');
+    
+    deepEqual(_.chunk([1, 2, 3], 0), [], 'chunk into parts of 0 elements returns an empty array');
+    deepEqual(_.chunk([1, 2, 3], -1), [], 'chunk into parts of negative amount of elements returns an empty array');
+    
+    deepEqual(_.chunk([1, 2, 3], 3), [[1, 2, 3]], 'chunk into parts of current array length elements returns the original array');
+    deepEqual(_.chunk([1, 2, 3], 5), [[1, 2, 3]], 'chunk into parts of more then current array length elements returns the original array');
+    
+    deepEqual(_.chunk([10, 20, 30, 40, 50, 60, 70], 2), [[10, 20], [30, 40], [50, 60], [70]], 'chunk into parts of less then current array length elements');
+    deepEqual(_.chunk([10, 20, 30, 40, 50, 60, 70], 3), [[10, 20, 30], [40, 50, 60], [70]], 'chunk into parts of less then current array length elements');
+  });
+  
 }());

underscore.js

@@ -696,6 +696,20 @@
     return range;
   };
 
+  // Split an **array** into several arrays containing **count** or less elements
+  // of initial array
+  _.chunk = function(array, count) {
+    var result = [];
+
+    if (array == null || count <= 0) return [];
+
+    for (var i = 0, length = array.length; i < length;) {
+      result.push(array.slice(i, i += count));
+    }
+
+    return result;
+  };
+
   // Function (ahem) Functions
   // ------------------