javascript picking tickets (maxTicket)

maxTicket.js

/* complete the function maxTicket to return the maximum subsqeunces in the given array, 
where the maximum absilute difference between elemnts in one subsqeunce j and j+1 is either 0 or 1 */
const maxTicket = (s) => {
  let subsequences = {};
  s.forEach((ss) => {
    subsequences[ss] = subsequences[ss] ? [...subsequences[ss], ss]: [ss];
    if(subsequences[ss+1]) {
      subsequences[ss+1] = [...subsequences[ss+1], ss];
    }
    if(subsequences[ss-1]) {
      subsequences[ss-1] = [...subsequences[ss-1], ss];
    }
  });
  let maxLength = 0;
  Object.keys(subsequences).forEach((k) => {
    if(subsequences[k].length > maxLength) maxLength = subsequences[k].length;
  })
  return maxLength;
}