// A generic function for checking to see if an input element has
  // a date entered into it
  function checkDate( elem ) {
      // Make sure that something is entered, and that it
      // looks like a valid MM/DD/YYYY date
      return !elem.value || /^\d{2}\/\d{2}\/\d{2,4}$/.test(obj.value);\; \}$// Get an input element to check
  var elem = document.getElementById("date");
  
  // Check to see if the field contains a valid date
  if ( ! checkDate( elem ) ) {
      alert( "Field is not a date." );
  }