Ok I really tried my best to solve this algorithm . This is my code so far. What am I doing wrong.
function fearNotLetter(str) {
let letter = "abcdefghijklmnopqrstuvwxyz";
let lettersArr = letter.split("").sort((a, b) => a - b);
for(let i = 0; i < lettersArr; i++) {
return str.indexOf(lettersArr[i]) === -1 ? lettersArr[i].join(''):undefined;
}
}
fearNotLetter("abce");