Ajax/PHP form validation [closed]
<script>
    $.validator.setDefaults({
    submitHandler: function() { alert("submitted!"); }
    });
    $(document).ready(function(){
    $("#signupForm").validate({
        rules: {
            firstname:{
                required: true,
                minlength: 2
            },
            lastname: "required",
            username: {
                required: true,
                minlength: 2
            },
            password: {
                required: true,
                minlength: 5
            },
            confirm_password: {
                required: true,
                minlength: 5,
                equalTo: "#password"
            },
            email: {
                required: true,
                email: true
            },
            topic: {
                required: "#newsletter:checked",
                minlength: 2
            },
            agree: "required"
        },
        messages: {
            firstname:{
                required:"Please enter your firstname",
                minlength: "Your firstname must be more than 2 characters"
            },
            lastname: "Please enter your lastname",
            username: {
                required: "Please enter a username",
                minlength: "Your username must consist of at least 2              characters"
            },
            password: {
                required: "Please provide a password",
                minlength: "Your password must be at least 5 characters long"
            },
            confirm_password: {
                required: "Please provide a password",
                minlength: "Your password must be at least 5 characters long",
                equalTo: "Please enter the same password as above"
            },
            email: "Please enter a valid email address",
            agree: "Please accept our policy"
        }
    })
});

    (function($) {
    $(document).ready(function() {
        $('#signupForm').ajaxSubmit(){
            $Ajax({
                type:  'POST',
                url: 'regprocess.php',
                dataType: 'json',
                success: function(json, textStatus){
                    $('#signupForm label .error').append(json);
                },
                error : function(xhr, textStatus, errorThrown){
                    alert: ('An error occurred! ' + ( errorThrown ? errorThrown : xhr.status )

                });

        };

    });
})
    (jQuery);
    </script>


And PHP......

    <?php
    //form processing
    //import form info

     $firstname = $_POST['firstname'];
     $lastname = $_POST['lastname'];
     $username = $_POST['username'];
     $email = $_POST['email'];
     $password = $_POST['password'];
     $confirm_password = $_POST['confirm_password'];
      $myArray[] = $errors;
    if(isset($_POST['submit'])) {
      function validate($data){
    //validate here, return array of errors
    if(!isset($data)){
        print 'Please enter your ' + $data;
        }
    else if(strlen($data) <=2){
        print 'Your ' + $data + 'must be more than 2 characters';
    }else{//data is fine send to encryption
     $data = true;
        return $data;
    };
     validate($firstname);
     validate($lastname);
     validate($username);

    function is_valid_email_address($email){
        $qtext = '[^\x0d\x22\xSc\x80-\xff]';
        $dtext = '[^\x0d\x5b-\x5d\x80-\xff]';
        $atom = '[^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c' .
        '\x3e\x40\x5b-\x5d\x7f-\xff]+';
        $quoted_pair = '\x5c[\x00-\x7f]';
        $domain_literal = "\x5b($dtext|$quoted_pair)*\x5d";
        $quoted_string = "\x22($qtext|$quoted_pair)*\x22";
        $domain_ref = $atom;
        $sub_domain = "($domain_ref|$domain_literal)";
        $word = "($atom|$quoted_string)";
        $domain = "$sub_domain(\x2e$word)*";
        $local_part = "$word(\x2e$word)*";
        $addr_spec = "$local_part\x40$domain";
        return preg_match("!^$addr_spec$!", $email)? 1 : 0;
    }
    if (is_valid_email_address($email)){
        print $email + 'is a valid email address';
    } else{
        print 'Please enter a valid email address';
        };


    function validate_password($password){
        if(!isset($password)){
            print 'Please provide a password';
        }else if(strlen($password) <=5){
            print 'Your password must be at least 5 charachters long';
        }
        else{return $password;}
    };

        function confirm_password($confirm_password){

            if ($password !== $confirm_password){
                print 'Please enter the same password as above';
            }else{ $password === $confirm_password;}
                return $confirm_password;
            }
            };

$ar=array("1"=>one,"2"=>"two");
$json=json_encode($ar);
echo $json;

function ajax(calledpage, errordiv)
{
    var xmlhttp;
    if (window.XMLHttpRequest)
        xmlhttp=new XMLHttpRequest();
    else
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    xmlhttp.onreadystatechange=function(){
        if (xmlhttp.readyState==4 && xmlhttp.status==200)
            document.getElementById(errordiv).innerHTML=xmlhttp.responseText;
    }
    xmlhttp.open("GET", calledpage, true);
    xmlhttp.send();
}

ajax('mypage.php?x=myvariable','my_error_divs_id');