Initial implementation of _.chunk - close #465

lodash.js

@@ -3998,6 +3998,35 @@
       return baseAt(collection, baseFlatten(arguments, true, false, 1));
     }
 
+    /**
+     * Creates an array of elements split into groups the length of `chunkSize`.
+     * If `collection` cannot be split evenly, the final chunk will be the remaining elements.
+     *
+     * @static
+     * @memberOf _
+     * @category Collections
+     * @param {Array|Object|string} collection The collection to iterate over.
+     * @param {numer} chunkSize The size of each chunk.
+     * @returns {Array} Returns the new array containing chunks.
+     * @example
+     *
+     * _.chunk(['a', 'b', 'c', 'd'], 2);
+     * // => [['a', 'b'], ['c', 'd']]
+     *
+     * _.chunk(['a', 'b', 'c', 'd'], 3);
+     * // => [['a', 'b', 'c'], ['d']]
+     */
+    function chunk(collection, chunkSize) {
+      var index = 0,
+          length = collection ? collection.length : 0,
+          result = [];
+
+      while (index < length) {
+        result.push(slice(collection, index, (index += chunkSize)));
+      }
+      return result;
+    }
+
     /**
      * Checks if `value` is present in `collection` using strict equality for
      * comparisons, i.e. `===`. If `fromIndex` is negative, it is used as the
@@ -8611,6 +8640,7 @@
     lodash.bindAll = bindAll;
     lodash.bindKey = bindKey;
     lodash.chain = chain;
+    lodash.chunk = chunk;
     lodash.compact = compact;
     lodash.compose = compose;
     lodash.constant = constant;

test/test.js

@@ -1211,6 +1211,29 @@
 
   /*--------------------------------------------------------------------------*/
 
+  QUnit.module('lodash.chunk');
+
+  (function() {
+    var array = [0, 1, 2, 3, 4, 5];
+
+    test('should return chunked arrays', 1, function() {
+      var actual = _.chunk(array, 3);
+      deepEqual(actual, [[0, 1, 2], [3, 4, 5]]);
+    });
+
+    test('should return the last chunk as remaining elements', 1, function() {
+      var actual = _.chunk(array, 4);
+      deepEqual(actual, [[0, 1, 2, 3], [4, 5]]);
+    });
+
+    test('should ignore falsey values', 1, function() {
+      var actual = _.chunk(false, 3);
+      deepEqual(actual, []);
+    });
+  }());
+
+  /*--------------------------------------------------------------------------*/
+
   QUnit.module('cloning');
 
   (function() {
@@ -10918,7 +10941,7 @@
 
     var acceptFalsey = _.difference(allMethods, rejectFalsey);
 
-    test('should accept falsey arguments', 187, function() {
+    test('should accept falsey arguments', 188, function() {
       var emptyArrays = _.map(falsey, _.constant([])),
           isExposed = '_' in root,
           oldDash = root._;