Sistema de Login com Ajax é seguro fazer isso?

Estou fazendo um sistema de login e cadastro, porem percebi que minhas variáveis ficam expostas no javascript, tem algum problema isso? é possível eu sofrer alguma quebra no sistema?

 <script type="text/javascript">
 function signin(){
 var name = $('#cpnome').val();
 var lastname = $('#cpsobrenome').val();
 var day = $('#cpselectdia').val();
 var month = $('#cpselectmes').val();
 var year = $('#cpselectano').val();
 var rg = $('#cprg').val();
 var cpf = $('#cpcpf').val();
 var dddphone = $('#cpdddphone').val();
 var phone = $('#cpphone').val();
 var dddsmartphone = $('#cpdddsmartphone').val();
 var smartphone = $('#cpsmartphone').val();
 var state = $('#cpselectestado').val();
 var city = $('#cpselectcidade').val();
 var neighborhood = $('#cpselectbairro').val();
 var street = $('#cprua').val();
 var number = $('#cpn').val();
 var cep = $('#cpcep').val();
 var email = $('#cpemail').val();
 var password = $('#cpsenha').val();
 var passwordconfirm = $('#cpsenhanovamente').val();
 $.ajax({
 url: 'signin.php',
 type: 'POST',
 data:
 'name='+name
 +'&lastname='+lastname
 +'&day='+day
 +'&month='+month
 +'&year='+year
 +'&rg='+rg
 +'&cpf='+cpf
 +'&dddphone='+dddphone
 +'&phone='+phone
 +'&dddsmartphone='+dddsmartphone
 +'&smartphone='+smartphone
 +'&state='+state
 +'&city='+city
 +'&neighborhood='+neighborhood
 +'&street='+street
 +'&number='+number
 +'&cep='+cep
 +'&email='+email
 +'&password='+password
 +'&passwordconfirm='+passwordconfirm
 }).done(function(resp){
 if (resp=='1') {
 //location.href='index.php';

 }else{
 document.getElementById("respsignin").style.display = "block";
 document.getElementById("respsignin").innerHTML=resp;
 }
 });
 }
 </script>