Get First Repeating Character Example

firstrepeatingchar.js

function getFirstRepeatingCharacter(someString) {
  let len = someString.length;
  let cache = {};
  
  for (let i = 0; i < len; i++) {
    let currentLetter = someString.charAt(i);
    if (cache[currentLetter]) return someString.charAt(i);
    cache[currentLetter] = true;
  }
  
  // no result
  return false;
}