update snippets 62-78

snippets/isString.md

@@ -6,6 +6,9 @@ Use `typeof` to check if a value is classified as a string primitive.
 
 ```js
 const isString = val => typeof val === 'string';
-// isString(10) -> false
-// isString('10') -> true
+```
+
+```js
+isString(10) -> false
+isString('10') -> true
 ```