Move internal modules to “internal” folder.

.internal/compareMultiple.js

@@ -0,0 +1,44 @@
+import compareAscending from './.internal/compareAscending.js';
+
+/**
+ * Used by `orderBy` to compare multiple properties of a value to another
+ * and stable sort them.
+ *
+ * If `orders` is unspecified, all values are sorted in ascending order. Otherwise,
+ * specify an order of "desc" for descending or "asc" for ascending sort order
+ * of corresponding values.
+ *
+ * @private
+ * @param {Object} object The object to compare.
+ * @param {Object} other The other object to compare.
+ * @param {boolean[]|string[]} orders The order to sort by for each property.
+ * @returns {number} Returns the sort order indicator for `object`.
+ */
+function compareMultiple(object, other, orders) {
+  let index = -1;
+  const objCriteria = object.criteria;
+  const othCriteria = other.criteria;
+  const length = objCriteria.length;
+  const ordersLength = orders.length;
+
+  while (++index < length) {
+    const result = compareAscending(objCriteria[index], othCriteria[index]);
+    if (result) {
+      if (index >= ordersLength) {
+        return result;
+      }
+      const order = orders[index];
+      return result * (order == 'desc' ? -1 : 1);
+    }
+  }
+  // Fixes an `Array#sort` bug in the JS engine embedded in Adobe applications
+  // that causes it, under certain circumstances, to provide the same value for
+  // `object` and `other`. See https://github.com/jashkenas/underscore/pull/1247
+  // for more details.
+  //
+  // This also ensures a stable sort in V8 and other engines.
+  // See https://bugs.chromium.org/p/v8/issues/detail?id=90 for more details.
+  return object.index - other.index;
+}
+
+export default compareMultiple;