function form_verif(form_id){
	
	// we define -----------------------
	form = document.getElementById(form_id);
	
	// we init -----------------------
	var keAlerte = "";
	
	// we verify -----------------------
	switch (form_id){
		
		
		case "form_contact" :
	
			if (form.nom.value == "" || form.nom.value == " ") keAlerte+="\nVeuillez remplir le champ \'Votre nom\'\n";
			if (form.prenom.value == "" || form.prenom.value == " ") keAlerte+="\nVeuillez remplir le champ \'Votre prénom\'\n";
			if (form.email.value == "" || form.email.value == " ") keAlerte+="\nVeuillez remplir le champ \'Votre adresse email\'\n";
			
			if (form.email.value != "" && !verif_mail(form.email.value)) keAlerte += "\nVotre adresse mail est invalide\r";
			
			
		break;
	
	}
	
	
	// we act -----------------------
	if (keAlerte!=""){
		alert(keAlerte);
		return false;
	}else{
		form.submit();
	}
	
	
}


function verif_mail(email){
		var arobase=email.indexOf("@");
		var point= email.lastIndexOf(".");
		if((arobase < 3)||(point + 2 > email.length) ||(point < arobase+3)){
			return false;
		}else{
			return true;
		}
}