Discussion on: Daily Challenge #60 - Find the Missing Letter

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Replies for: This makes an assumption about where the missing letter is in the string that isn't valid for all the test cases? It returns incorrectly for both ...

Thanks for the heads up. I did not get the challenge right and posted a wrong answer. Here is the correct one, I hope :)

missingL = input => {
  const alphabet = [
    "a","b","c","d","e","f","g",
    "h","i","j","k","l","m","n",
    "o","p","q","r","s","t","u",
    "v","w","x","y","z"
  ];

  const alphabetUp = alphabet.map(item => item.toUpperCase());

  input[0] == input[0].toUpperCase()
    ? alphabet.splice(0, 26, ...alphabetUp)
    : alphabet;
  const compareArray = alphabet.slice(
    alphabet.indexOf(input[0]),
    alphabet.indexOf(alphabet[alphabet.indexOf(input[0]) + input.length])
  );

  return compareArray.filter(item => !input.includes(item));
};