// JavaScript Document
function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}

function MM_swapImgRestore() { //v3.0
  var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}

function MM_findObj(n, d) { //v4.01
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
  if(!x && d.getElementById) x=d.getElementById(n); return x;
}

function MM_swapImage() { //v3.0
  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
   if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}

function openPop(theUrl,theName,theSpecs) {
	var popWidth=screen.availWidth-10;
	var popHeight=screen.availHeight-20;
	var theSpecs="width="+popWidth+",height="+popHeight+",scrollbars=yes,resizable=yes,left=0,top=0";
	window.open(theUrl,theName,theSpecs)
}

<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->
<!-- Begin
function checkFields() {
missinginfo = "";
if (document.prenot.Nome_e_Cognome.value == "") {
missinginfo += "\n     -  First and Last Name";
}
if (document.prenot.Tipo_Appartamento.value == "") {
missinginfo += "\n     -  Kind of Apartment";
}
if (document.prenot.Numero_Persone.value == "") {
missinginfo += "\n     -  Number of Persons";
}
if(document.prenot.Telefono.value == "") {
missinginfo += "\n     -  Telephone number";
}
if (missinginfo != "") {
missinginfo ="_____________________________\n" +
"The following fields have not been filled out properly:\n" +
missinginfo + "\n_____________________________" +
"\nPlease reinsert data and click Send!";
alert(missinginfo);
return false;
}
else return true;
}