function viewcalendar() {
  calendar = window.open("calendar.php", "calendar" , "location=0, menubar=0, scrollbars=0, status=0, titlebar=0, toolbar=0, directories=0, resizable=1, width=200, height=240, top=100, left=250");
  calendar.resizeTo(700, 300);
  calendar.moveTo(250, 50);
}

function insertdate(d) {
  window.close();
  window.opener.document.getElementById('date').value = d;
}