// JavaScript Document
function checkForm() {
  	var error = 0;
  	var review = document.getElementById("product_reviews_write").review.value;

  	if (review.length <= 1 ) {
   	error = 1;
 	 }

if (!((document.getElementById("product_reviews_write").rating[0].checked) || (document.getElementById("product_reviews_write").rating[1].checked) || (document.getElementById("product_reviews_write").rating[2].checked) || (document.getElementById("product_reviews_write").rating[3].checked) || (document.getElementById("product_reviews_write").rating[4].checked))) {
    	error = 1;
 	 }

  	if (error == 1) {
    	alert("Notwendige Angaben fehlen!");
    	return false;
  	} else {
    	return true;
  	}
}

*****************************************************************
-JavaScript-Code in folgender PHP-IF-Bedingung löschen:
  if (strstr($PHP_SELF, FILENAME_PRODUCT_REVIEWS_WRITE )) {