Update indexOfAll.md

snippets/indexOfAll.md

@@ -1,6 +1,9 @@
 ### indexOfAll
 
-Returns an array of indexes at which the `val` occurs in `arr`. If it occurs only once return the `index` and if it never occurs returns `-1`
+Returns all indices of `val` in an array. If `val` never occurs, returns `[-1]`.
+
+Use `Array.forEach()` to loop over elements and `Array.push()` to store indices for matching elements.
+Return `[-1]` if `length` of the array of indices is `0`, otherwise return the array of indices.
 
 ``` js
 const indexOfAll = (arr, val) => {
@@ -10,9 +13,8 @@ const indexOfAll = (arr, val) => {
 };
 
 ```
+
 ``` js
-indexOfAll([1,2,3],1); // [0]
 indexOfAll([1,2,3,1,2,3],1); // [0,3]
 indexOfAll([1,2,3],4); // [-1]
-indexOfAll([[1,2,3]],[1,2,3]); // [-1] (Array.prototype.indexOf()) has the same behaviour
 ```