Update mask.md

snippets/mask.md

@@ -7,8 +7,7 @@ Omit the second argument, `num`, to keep a default of `4` characters unmasked. I
 Omit the third argument, `mask`, to use a default character of `'*'` for the mask.
 
 ```js
-const mask = (cc, num = 4, mask = '*') =>
-  ('' + cc).slice(-num).padStart(('' + cc).length, mask);
+const mask = (cc, num = 4, mask = '*') => `${cc}`.slice(-num).padStart(`${cc}`.length, mask);
 ```
 
 ```js