js 现在时间到当天24时结束

获取到时间差为毫秒，可以转为时分秒，自行处理，

getTimestamp(){
  let nowB = new Date().getTime()
  let form = new Date()
  let y = form.getFullYear();
  let m = form.getMonth()+1;
  let d = form.getDate();
  let nowE = new Date(y,m,d,"23","59","59").getTime()
  return nowE - nowB
}