Merge pull request #2252 from megawac/chunk

Chunk

test/arrays.js

@@ -539,4 +539,19 @@
     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([1, 2, 3], 0), [], 'chunk into parts of 0 elements returns 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]), [], 'defaults to empty array (chunk size 0)');
+
+    deepEqual(_.chunk([1, 2, 3], 1), [[1], [2], [3]], 'chunk into parts of 1 elements returns original 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 +696,19 @@
     return range;
   };
 
+  // Split an **array** into several arrays containing **count** or less elements
+  // of initial array
+  _.chunk = function(array, count) {
+    if (count == null || count < 1) return [];
+
+    var result = [];
+    var i = 0, length = array.length;
+    while (i < length) {
+      result.push(slice.call(array, i, i += count));
+    }
+    return result;
+  };
+
   // Function (ahem) Functions
   // ------------------