Travis build: 740 [ci skip]

README.md

@@ -265,6 +265,15 @@
 
 </details>
 
+### _Uncategorized_
+
+<details>
+<summary>View contents</summary>
+
+* [`sortedIndex`](#sortedindex)
+
+</details>
+
 ---
  ## 🔌 Adapter
 
@@ -4515,6 +4524,31 @@ yesNo('Foo', true); // true
 
 <br>[⬆ Back to top](#table-of-contents)
 
+---
+ ## _Uncategorized_
+
+### sortedIndex
+
+Returns the lowest index at which value should be inserted into array in order to maintain its sort order.
+
+Check if the array is sorted in descending order (loosely).
+Use `Array.findIndex()` to find the appropriate index where the element should be inserted.
+
+```js
+const sortedIndex = (arr, n) => {
+  const isDescending = arr[0] > arr[arr.length - 1];
+  const index = arr.findIndex(el => (isDescending ? n >= el : n <= el));
+  return index === -1 ? arr.length : index;
+};
+```
+
+```js
+sortedIndex([5, 3, 2, 1], 4); // 1
+sortedIndex([30, 50], 40); // 1
+```
+
+<br>[⬆ back to top](#table-of-contents)
+
 
 ## Collaborators