从php cUrl返回的Ajax没有任何价值

When I click the submit button, there's an ajax post request. But then the returned json value has only "" in it. Even the console.log(data) is not working when the .done() ajax is fired up.

<form id="form" action="#">
    <input type="email" placeholder="email" id="account_name" name="account_name" value="email@test.com"> <br>
    <input type="text" placeholder="First Name" id="first_name"  name="first_name" value="volvo"><br>
    <input type="text" placeholder="Last Name" id="last_name"  name="last_name" value="volva"><br>
    <input type="submit" name="submit" id="btn"/>
</form>

    <script type="text/javascript">
        $(function(){
            var btn = $("#btn");
            var form = $("#form");
            var accName =$("#account_name").val();

            form.on("submit",function(evt){
                evt.preventDefault();
                var myReq = $.ajax({
                    method:"POST",
                    url:"create.php",
                    dataType: 'json',
                    data: "account_name="+accName
                });
                myReq.done(createAcct);
            });

            function createAcct(data){
                console.log(data);
                var a = JSON.parse(data);
                console.log(typeof a);

            }    
        });
    </script>

So the returned json is this {"ac":""}Array in the response tab. Here's my php curl

$ca = createAcct($_REQUEST['account_name']);

$data = ["ca"=>"$ca"];//should be the email
print json_encode($data);
echo $data;

function createAcct($email_account){
    $data = '{"account_name":"'.$email_account.'"}';
    $ch = curl_init();

    //Set cURL parameters to perform API Call
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_URL, "https://api.website.com/api/accounts/create");
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_USERPWD, API_USER.':'.API_PASS);
    curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));
    curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
    $statusCode = curl_getinfo($ch,CURLINFO_HTTP_CODE);

    $output = curl_exec($ch);
    $err = curl_error($ch);
    if ($statusCode == 204) {
        return $email_account;
        curl_close($ch);
    } else {
        curl_close($ch);
    }

}

First of all you change

print json_encode($data);    
echo $data;

To

echo json_encode($data);

Than it's better way to get response direct with ajax like this

$.ajax({
    method:"POST",
    url:"call.php",
    dataType: 'json',
    data: "account_name="+accName
}).done(function(data) {
    createAcct(data);
});

Now in createAcct function you get response

function createAcct(data){
    console.log("f");
    console.log(data);
    console.log(data['ca']);
    console.log(typeof data);
}   

You can also use ajax success replace of done function

success : function(data) {
    createAcct(data);
}

pass 'Content-Length: ' . strlen($data))