Return True If The String In The First Element Of The Array Contains All Of The Letters Of The String In The Second Element

function mutation(arr) {
  return arr;
}

mutation(["hello", "hey"]);

• For example, ["hello", "Hello"], should return true because all of the letters in the second string are present in the first, ignoring case.
• The arguments ["hello", "hey"] should return false because the string hello does not contain a y.

Hint:

• If everything is lowercase it will be easier to compare.
• Our strings might be easier to work with if they were arrays of characters.

• A loop might help. Use indexOf() to check if the letter of the second word is on the first.

• Answer:
  

function mutation(arr) {
   let firstWord = arr[0].toLowerCase();
   let secondWord = arr[1].toLowerCase();

   for (let i = 0; i < secondWord.length; i++) {
    let letters = secondWord[i];
    if (firstWord.indexOf(letters) === -1) return false;
   }
      return true;
 }

mutation(["hello", "hey"]); // will display false