Answer by zVictor for Detecting an "invalid date" Date instance in JavaScript

I combined the best performance results I found around that check if a given object:

• is a Date instance (benchmark here)
• has a valid date (benchmark here)

The result is the following:

function isValidDate(input) {
  if(!(input && input.getTimezoneOffset && input.setUTCFullYear))
    return false;

  var time = input.getTime();
  return time === time;
};