Bump to v3.10.0.

internal/baseFlatten.js

@@ -1,3 +1,4 @@
+import arrayPush from './arrayPush';
 import isArguments from '../lang/isArguments';
 import isArray from '../lang/isArray';
 import isArrayLike from './isArrayLike';
@@ -11,13 +12,14 @@ import isObjectLike from './isObjectLike';
  * @param {Array} array The array to flatten.
  * @param {boolean} [isDeep] Specify a deep flatten.
  * @param {boolean} [isStrict] Restrict flattening to arrays-like objects.
+ * @param {Array} [result=[]] The initial result value.
  * @returns {Array} Returns the new flattened array.
  */
-function baseFlatten(array, isDeep, isStrict) {
+function baseFlatten(array, isDeep, isStrict, result) {
+  result || (result = []);
+
   var index = -1,
-      length = array.length,
-      resIndex = -1,
-      result = [];
+      length = array.length;
 
   while (++index < length) {
     var value = array[index];
@@ -25,16 +27,12 @@ function baseFlatten(array, isDeep, isStrict) {
         (isStrict || isArray(value) || isArguments(value))) {
       if (isDeep) {
         // Recursively flatten arrays (susceptible to call stack limits).
-        value = baseFlatten(value, isDeep, isStrict);
-      }
-      var valIndex = -1,
-          valLength = value.length;
-
-      while (++valIndex < valLength) {
-        result[++resIndex] = value[valIndex];
+        baseFlatten(value, isDeep, isStrict, result);
+      } else {
+        arrayPush(result, value);
       }
     } else if (!isStrict) {
-      result[++resIndex] = value;
+      result[result.length] = value;
     }
   }
   return result;