Bump to v4.0.0.

sortBy.js

@@ -0,0 +1,52 @@
+import baseFlatten from './internal/baseFlatten';
+import baseOrderBy from './internal/baseOrderBy';
+import isIterateeCall from './internal/isIterateeCall';
+import rest from './rest';
+
+/**
+ * Creates an array of elements, sorted in ascending order by the results of
+ * running each element in a collection through each iteratee. This method
+ * performs a stable sort, that is, it preserves the original sort order of
+ * equal elements. The iteratees are invoked with one argument: (value).
+ *
+ * @static
+ * @memberOf _
+ * @category Collection
+ * @param {Array|Object} collection The collection to iterate over.
+ * @param {...(Function|Function[]|Object|Object[]|string|string[])} [iteratees=[_.identity]]
+ *  The iteratees to sort by, specified individually or in arrays.
+ * @returns {Array} Returns the new sorted array.
+ * @example
+ *
+ * var users = [
+ *   { 'user': 'fred',   'age': 48 },
+ *   { 'user': 'barney', 'age': 36 },
+ *   { 'user': 'fred',   'age': 42 },
+ *   { 'user': 'barney', 'age': 34 }
+ * ];
+ *
+ * _.sortBy(users, function(o) { return o.user; });
+ * // => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 42]]
+ *
+ * _.sortBy(users, ['user', 'age']);
+ * // => objects for [['barney', 34], ['barney', 36], ['fred', 42], ['fred', 48]]
+ *
+ * _.sortBy(users, 'user', function(o) {
+ *   return Math.floor(o.age / 10);
+ * });
+ * // => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 42]]
+ */
+var sortBy = rest(function(collection, iteratees) {
+  if (collection == null) {
+    return [];
+  }
+  var length = iteratees.length;
+  if (length > 1 && isIterateeCall(collection, iteratees[0], iteratees[1])) {
+    iteratees = [];
+  } else if (length > 2 && isIterateeCall(iteratees[0], iteratees[1], iteratees[2])) {
+    iteratees.length = 1;
+  }
+  return baseOrderBy(collection, baseFlatten(iteratees), []);
+});
+
+export default sortBy;