Advanced freeCodeCamp • intermediate-algorithm-scripting

Missing letters

Challenge Overview

Find the missing letter in the passed letter range and return it.

If all letters are present in the range, return undefined.

💡 View Solution

function fearNotLetter(str) {
  for (let i = 0; i < str.length; i++) {
    const code = str.charCodeAt(i);
    if (code !== str.charCodeAt(0) + i) return String.fromCharCode(code - 1);
  }
  return undefined;
}