function showPrevious() {
  if (currentPhotoIndex > 0) {
    currentPhotoIndex -= 1;
    document.getElementById("placePhoto").innerHTML = photoURLArray[currentPhotoIndex];
  }
}

function showNext() {
  if (currentPhotoIndex < photoURLArray.length - 1) {
    currentPhotoIndex += 1;
    document.getElementById("placePhoto").innerHTML = photoURLArray[currentPhotoIndex];
  }
}

<!-- Begin
function popUp(NAME,URL) {
day = new Date();
id = day.getTime();
eval("page" + id + " = window.open(URL, '" + id + "', 'toolbar=0,scrollbars=1,location=0,statusbar=0,menubar=0,resizable=1,width=800,height=600');");
}
// End -->