查找字符串中倒数第二个出现的字符

function findSecondLastChar(str) {
  let lastChar = '';
  let secondLastChar = '';

  for (let i = 0; i < str.length; i++) {
    if (str[i] === lastChar) {
      secondLastChar = lastChar;
    }
    lastChar = str[i];
  }

  return secondLastChar;
}

const inputString = 'Hello World';
const secondLastChar = findSecondLastChar(inputString);
console.log('倒数第二个出现的字符是：', secondLastChar);