function check_form(x) {

  		for (i=0;i<x.length;i++) {

			var tmp=x.elements[i];

    			if (tmp.type=="select-one") { 

				var boxLength 	= tmp.length;

				for (j = 0; j < boxLength; j++) {
					if (tmp.options[j].selected && tmp.options[j].value != 0)
	      					return true;
				}
			}
  		}

		alert ("Please select a product to add to the shoppingcart");

		return false;

	} <!-- end of function -->