How to parse an objects with array index to object array with key value pairs

function parseObject(input) {
  const result = {};
  Object.keys(input).forEach((key) => {
    const index = key.indexOf("[");
    if (index > -1) {
      const root = key.substring(0, index);
      const subKey = key.substring(index + 1, key.length)
      const indexNum = parseInt(subKey, 10);
      if (!result[root]) {
        result[root] = [];
      }
      if (!result[root][indexNum]) {
        result[root][indexNum] = {};
      }
      result[root][indexNum][subKey.substring(subKey.indexOf(".") + 1)] = input[key];
    } else {
      result[key] = input[key];
    }
  });
  return result;
}
const input = {"SubmitBy":"SK", "Students[0].name":"Jhon", "Students[0].age":"15", "Students[1].name":"Sam", "Students[1].age":"16", "Students[2].name":"Tom", "Students[2].age":15};
const output = parseObject(input);
console.log(output);