function show_error()
{
alert("Erreur : veuillez remplir les champs requis");
}

function validate_field(field)
{
if (field.value.length == 0) {return false}
else {return true}
}

function validate_email(field)
{
with (field)
 {
apos=value.indexOf("@")
dotpos=value.lastIndexOf(".")
if (apos<1||dotpos-apos<2) 
  {alert("Erreur : adresse e-mail non valide");return false}
else {return true}
 }
}

function validate_newsletter(thisform)
{
with (thisform)
 {
if (validate_field(last_name)==false || validate_field(email)==false) 
  {show_error(); return false}
if(validate_email(email)==false)
 return false
 }
}

function validate_form(thisform)
{
with (thisform)
 {
if (validate_field(last_name)==false || validate_field(phone)==false || validate_field(email)==false || validate_email(email)==false)
  {show_error(); return false}
 }
}

function is_date(thisdate)
{
var exp = new RegExp("^[0-9-/h .]+$","g");
return exp.test(thisdate.value);
}

function validate_callback(thisform)
{
with (thisform)
 {
if (validate_field(nom)==false || validate_field(phone)==false || is_date(date)==false)
  {show_error(); return false}
 }
}