I'm working on my last JavaScript project for school and have encountered a few problems. My teacher seems to be MIA so any help would be greatly appreciated. The two issues that I'm having with this script are:
- The cookies only work in Internet Explorer;
- I can't figure out the code to save the 3rd text input field as a cookie that will automatically change the background color to the user's fav color.

Thoughts?

Code:
<html>
<head>
<title>Exercice 07</title>

<script language="javascript">

<!-- Début

//Valider formulaire
function valider(){

var bgColor = document.testform.Couleur.value;
    document.bgColor = bgColor;

if (document.testform.Prenom.value=="") {
alert("S.V.P. indiquez votre prénom!")
return false;
}
if (document.testform.Nom.value=="") {
alert("S.V.P. indiquez votre nom de famille!")
return false;
}
if (document.testform.Couleur.value=="") {
alert("S.V.P. indiquez votre couleur préféré!")
return false;
}

var inputField = document.getElementById("Couleur").value.substr(1);
if (!/^[a-f0-9]{3}$|^[a-f0-9]{6}$/i.test(inputField))
{
	alert("Vous devez indiquez une valeur hexidécimale!");
}

return true;

}

function set_it() {

  var inputFieldP = document.getElementById("Prenom").value
  var inputFieldN = document.getElementById("Nom").value
  var thetext="greeting=Bonjour, "+inputFieldP +" " +inputFieldN +",";
  var expdate=";expires=Mon, 30 Mar 2020 13:00:00 UTC";
  var newtext=escape(thetext);
  newtex+=expdate;
  document.cookie=newtext
  
}

function read_it() {

 var mycookie =document.cookie;
 var fixed_cookie = unescape(mycookie);
 var thepairs = fixed_cookie.split(";");
 var namepairs= thepairs[0].split("=");
 var greet= namepairs[1];
 document.write(greet);
 }

if (document.cookie) {
  read_it();
}
else {
  set_it();
}

// Fin -->
</script>

</head>
<body>

<script language="javascript">
  //Message de bienvenue en fonction de l'heure
  var heure=new Date().getHours()
  var msg=""
  if (heure<=6) {msg="bonne nuit"}
  if (heure>6 && heure<=12) {msg="bon matin"}
  if (heure>12 && heure<=18) {msg="bonne après-midi"}
  if (heure>18 && heure<=24) {msg="bonne soirée"}
  
  document.write(msg +"!");  
  
</script>
<h2>Pr&eacute;f&eacute;rences usager:</h2>
<form name="testform" >
Prénom:&nbsp;<input size="30" id="Prenom" value="Visiteur" onblur="valider()" type="text"><br>
Nom:&nbsp;<input size="30" id="Nom" value="Inconnu" valider()" type="text"><br>
Couleur préféré:&nbsp;<input size="30" id="Couleur" value="#FFFFFF" onblur="valider()" maxlength="7" type="text"><br>
<input value="Sauvegarder" type="button" onClick="set_it()">
<input value="Visualiser" type="button" onClick="window.location.reload()">
</form>
</body>
</html>