fix: explain method chaining for step 18 of music player (#53693)

curriculum/challenges/english/15-javascript-algorithms-and-data-structures-22/learn-basic-string-and-array-methods-by-building-a-music-player/654215fe7b4a899ddceb3b60.md

@@ -7,9 +7,9 @@ dashedName: step-18
 
 # --description--
 
-Use the `join()` method to combine the `songsHTML` markup into a single string.
+Right now the `songsHTML` is an array. If you tried to display this as is, you would see the songs separated by commas. This is not the desired outcome because you want to display the songs as a list. To fix this, you will need to join the array into a single string by using the <dfn>join()</dfn> method.
 
-The `join()` method is used to concatenate all the elements of an array into a single string. It takes an optional parameter called `separator` which is used to separate each element of the array. For example:
+The `join()` method is used to concatenate all the elements of an array into a single string. It takes an optional parameter called a `separator` which is used to separate each element of the array. For example:
 
 ```js
 const exampleArr = ["This", "is", "a", "sentence"];
@@ -19,6 +19,12 @@ console.log(sentence); // Output: "This is a sentence"
 
 Chain the `join()` method to your `map()` method and pass in an empty string for the separator.
 
+To chain multiple methods together, you can call the `join()` method on the result of the `map()` method. For example:
+
+```js
+array.map().join();
+```
+
 # --hints--
 
 You should add `join("")` to the existing code.