回答編集履歴

 

  let str = '2400-2-29';

  let reg = /^(?:(?!(?:[02468][1235679]|[13579][01345789])00[年\-/]0?2[月/\-](?:29|30)日?))(?:(?![0-9]{2}(?:[02468][1235679]|[13579][01345789])[年\-/]0?2[月/\-](?:29|30)日?))(?:(?![0-9]{4}[年\-/](?:0?2|0?4|0?6|0?9|11)[月/\-]31日?))([0-9]{4})[年\-/](0?[1-9]|1[0-2])[月/\-](0?[1-9]|[12][0-9]|3[01])日?$/;

 

  let date = (n = reg.exec(str)) ? new Date (n[1], n[2]-1, n[3]): null;

  console.log(date);