const assert = require('assert');

const countVowels = str => Array.from(str)
  .filter(letter => 'aeiou'.includes(letter)).length;

console.log(countVowels('abcdefghijklmnopqrstuvwxyz')); // 5
console.log(countVowels('December')); // 3
console.log(countVowels('xxx')); // 0



@@ -269,9 +269,62 @@
 ; // 0%0A%0A
+const a1 = %22vowels%22;%0Aconst r1 = %22array%22;%0A%0Aassert(r1);
 %0A

edit input for example