function validator() {
if (!document.getElementById("contact-form")) { return false; }
var form = document.getElementById("contact-form");

form.onsubmit = function() {
var errors = 0;
$('#contact-form li.error span').remove();
$("li").removeClass("error");

var firstname = document.getElementById("conname");
if(firstname.value === '') {
errors[errors++]
$(firstname.parentNode).addClass("error").append('<span>Name fehlt</span>');
}

var email = document.getElementById("conemail");
if(email.value === '') {
errors[errors++]
$(email.parentNode).addClass("error").append('<span>E-Mail fehlt</span>');
} else {
if (!validEmail(email.value)){
errors[errors++]
$(email.parentNode).addClass("error").append('<span>Sie haben eine falsche E-Mail Adresse eingegeben</span>');
}
}

var message = document.getElementById("conmessage");
if(message.value === '') {
errors[errors++]
$(message.parentNode).addClass("error").append('<span>Nachricht fehlt</span>');
}

if (errors != 0) {
return false;
}

}
}

$(document).ready(function(){
validator();
});