Bump to v3.6.0.

math/sum.js

@@ -1,4 +1,8 @@
-var isArray = require('../lang/isArray'),
+var arraySum = require('../internal/arraySum'),
+    baseCallback = require('../internal/baseCallback'),
+    baseSum = require('../internal/baseSum'),
+    isArray = require('../lang/isArray'),
+    isIterateeCall = require('../internal/isIterateeCall'),
     toIterable = require('../internal/toIterable');
 
 /**
@@ -8,26 +12,41 @@ var isArray = require('../lang/isArray'),
  * @memberOf _
  * @category Math
  * @param {Array|Object|string} collection The collection to iterate over.
+ * @param {Function|Object|string} [iteratee] The function invoked per iteration.
+ * @param {*} [thisArg] The `this` binding of `iteratee`.
  * @returns {number} Returns the sum.
  * @example
  *
- * _.sum([4, 6, 2]);
- * // => 12
+ * _.sum([4, 6]);
+ * // => 10
  *
- * _.sum({ 'a': 4, 'b': 6, 'c': 2 });
- * // => 12
+ * _.sum({ 'a': 4, 'b': 6 });
+ * // => 10
+ *
+ * var objects = [
+ *   { 'n': 4 },
+ *   { 'n': 6 }
+ * ];
+ *
+ * _.sum(objects, function(object) {
+ *   return object.n;
+ * });
+ * // => 10
+ *
+ * // using the `_.property` callback shorthand
+ * _.sum(objects, 'n');
+ * // => 10
  */
-function sum(collection) {
-  if (!isArray(collection)) {
-    collection = toIterable(collection);
+function sum(collection, iteratee, thisArg) {
+  if (thisArg && isIterateeCall(collection, iteratee, thisArg)) {
+    iteratee = null;
   }
-  var length = collection.length,
-      result = 0;
+  var noIteratee = iteratee == null;
 
-  while (length--) {
-    result += +collection[length] || 0;
-  }
-  return result;
+  iteratee = noIteratee ? iteratee : baseCallback(iteratee, thisArg, 3);
+  return noIteratee
+    ? arraySum(isArray(collection) ? collection : toIterable(collection))
+    : baseSum(collection, iteratee);
 }
 
 module.exports = sum;