function numbersonly(myfield, e, dec)
{
var key;
var keychar;

if (window.event)
   key = window.event.keyCode;
else if (e)
   key = e.which;
else
   return true;
keychar = String.fromCharCode(key);

// control keys
if ((key==null) || (key==0) || (key==8) || 
    (key==9) || (key==13) || (key==27) )
   return true;

// numbers
else if ((("0123456789").indexOf(keychar) > -1))
   return true;

// decimal point jump
else if (dec && (keychar == "."))
   {
   myfield.form.elements[dec].focus();
   return false;
   }
else
   return false;
}
<!-- Fading Images -->
nereidFadeObjects = new Object();
nereidFadeTimers = new Object();
function nereidFade(object, destOp, rate, delta){
if (!document.all)
return
    if (object != "[object]"){  
        setTimeout("nereidFade("+object+","+destOp+","+rate+","+delta+")",0);
        return;
    }
        
    clearTimeout(nereidFadeTimers[object.sourceIndex]);
    
    diff = destOp-object.filters.alpha.opacity;
    direction = 1;
    if (object.filters.alpha.opacity > destOp){
        direction = -1;
    }
    delta=Math.min(direction*diff,delta);
    object.filters.alpha.opacity+=direction*delta;
    if (object.filters.alpha.opacity != destOp){
        nereidFadeObjects[object.sourceIndex]=object;
        nereidFadeTimers[object.sourceIndex]=setTimeout("nereidFade(nereidFadeObjects["+object.sourceIndex+"],"+destOp+","+rate+","+delta+")",rate);
    }
}
//

change_dropdown = function (obj, nb_dvd, nb_livre, totalcommande_obj, fraisdeport_obj, total_obj)
{
	var xhr;

	try 
	{
		xhr = new XMLHttpRequest();
	} 
	catch (e) 
	{
		var a = ['MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP', 'MICROSOFT.XMLHTTP.1.0 ', 'MICROSOFT.XMLHTTP.1', 'MICROSOFT.XMLHTTP'];
		for (var i = 0; i < a.length; i++) 
		{
			try 
			{
				xhr = new ActiveXObject(a[i]);
				break;
			} 
			catch (e) {}
		}
	}

	xhr.onreadystatechange = function()
	{
		if(xhr.readyState==4)
		{
			//alert(xhr.responseText);
			var xmlDoc = xhr.responseXML.documentElement;
			var prix = xmlDoc.getElementsByTagName("prix")[0].childNodes[0].nodeValue;
			var frai_de_por = parseFloat(prix);
			document.getElementById(fraisdeport_obj).value = frai_de_por + ' €';
			document.getElementById(total_obj).value = Math.round((parseFloat(document.getElementById(totalcommande_obj).value) + parseFloat(frai_de_por))*100)/100 + ' €';
			
		}
	}
	var rec_value = obj.options[obj.options.selectedIndex].value;
	xhr.open("GET", "get_tarifs.php?id_pays=" + rec_value + "&nb_dvd=" + nb_dvd + "&nb_livre=" + nb_livre, true);
	xhr.send(null);
}

function check()
{
	if (order.nom.value == ""){ 
        alert ("First name is required" )
        order.nom.focus()        
		 return;}
	else if (order.prenom.value == ""){ 
        alert ("Last name is required" )
        order.prenom.focus()        
		 return;}
	else if (order.adresse.value == ""){ 
        alert ("Address is required" )
        order.adresse.focus()        
		 return;}
	else if (order.code.value == ""){ 
        alert ("Postal Code is required" )
        order.code.focus()        
		 return;}
	else if (order.ville.value == ""){ 
        alert ("Ville is required" )
        order.ville.focus()        
		 return;}
	else if (order.pays.value == ""){ 
        alert ("Pays is required" )
        order.pays.focus()        
		 return;}
	else if (order.email.value == ""){ 
        alert ("Email is required" )
        order.email.focus()        
		 return;}
	else if(!((order.email.value.indexOf(".") > 2) && (order.email.value.indexOf("@") > 0))){
        alert ("Email is invalid" )
        order.email.focus()        
		 return;}
	else{
        document.order.submit();}
}

function check_fr()
{
	if (order.nom.value == ""){ 
        alert ("Le nom est obligatoire" )
        order.nom.focus()        
		 return;}
	else if (order.prenom.value == ""){ 
        alert ("Le prenom est obligatoire" )
        order.prenom.focus()        
		 return;}
	else if (order.adresse.value == ""){ 
        alert ("L'adresse est obligatoire" )
        order.adresse.focus()        
		 return;}
	else if (order.code.value == ""){ 
        alert ("Le Code postal est obligatoire" )
        order.code.focus()        
		 return;}
	else if (order.ville.value == ""){ 
        alert ("La ville est obligatoire" )
        order.ville.focus()        
		 return;}
	else if (order.pays.value == ""){ 
        alert ("Le pays est obligatoire" )
        order.pays.focus()        
		 return;}
	else if (order.email.value == ""){ 
        alert ("Le email est obligatoire" )
        order.email.focus()        
		 return;}
	else if(!((order.email.value.indexOf(".") > 2) && (order.email.value.indexOf("@") > 0))){
        alert ("Le email est incorrecte" )
        order.email.focus()        
		 return;}
	else{
        document.order.submit();}
}

function ordersubmit()
{
	if (order.q2.value > 5){ 
        alert ("Pour toute commande supérieur a 5 livres, s'adresse directement a Morgan Monchaud, responsable commercial via le formulaire de contact." )
        order.q2.focus()        
		 return;}
	else{
        document.order.submit();}
}