Function to determine whether a word is an isogram or not.

isogram.js

function isIsogram(check){
  if (check) {
  for (let i = 0; i < check.length; i++) {
    for (let j = i + 1; j < check.length; j++) {
      if (check[i] === check[j]) return false;
    } 
  }
  return true; 
}
return 'Invalid Entry!'
}

isIsogram('abcdefghijklmnopqrstuvwxyz');

function isIsogram(check) {
  if (check) {
    for (let i = 0; i < check.length; i++) {
      for (let j = i + 1; j < check.length; j++) {
        if (check[i] === check[j]) return false;
      }
    }
    return true;
  }
}

isIsogram('abcdefghijklmnopqrstuvwxyzz'); //return false
// Nice Job