Ajax成功未被调用，而请求成功发送

Here is my code:

<script src="https://code.jquery.com/jquery-3.3.1.js"></script>
<script>
  $(document).ready(function() {
    $("#btnSubmit").click(function() {
      $.ajax({
        type: "POST",
        url: "deepak.php",
        datatype: "html",
        data: 'Name=' + $("#name").val() + '&Email=' + $("#email").val() + '&password=' + $("#password").val() + '&cnfpassword=' + $("#cnfpassword").val(),
        success: function(result) {
          if (result == 'success') {
            alert("Ajax Successfully Executed")
          }
        }
      });
    });
  });
</script>

In my php code "success" message is generated via echo function. ajax works fine , it makes the required request. The only part is not working is the success.

here is my server-side code :

<?php //Database credentials $dbHost     = 'localhost'; $dbUsername = 'root'; $dbPassword = ''; $dbName     = 'fmc';

//Connect and select the database $db = new mysqli($dbHost, $dbUsername, $dbPassword, $dbName);

if($db){
    echo 'connected'; } else {
    echo "disconnected"; }


 $name = $_POST['Name'];  $email = $_POST['Email'];  $password = $_POST['password'];  $cnfpassword = $_POST['cnfpassword'];  

    $sql = "INSERT INTO seeifyouqualify (name, email, password, cnfpassword) VALUES ('$name', '$email', '$password', '$cnfpassword')";
    $query = mysqli_query($db, $sql);


 if(mysqli_query($db, $sql)){
    echo "success";  } ?>

Instead of send all inputs data what you can do is send the form data serialized like this:

<script>
  $(document).ready(function() {
    var formData = $("form#yourformId").serialize();
    $("#btnSubmit").click(function() {
      $.ajax({
        type: "POST",
        url: "deepak.php",
        datatype: "html",
        data: {'data_name': formData},
        success: function(result) {
          if (result == 'success') {
            alert("Ajax Successfully Executed")
          }
        }
      });
    });
  });
</script>

Also what I did above is send the data with a name because we have to catch it in php like:

<?php

    if(isset($_POST['data_name'])){
        //do something....
    }

?>

It's important to use if(isset(...)) because let's say someone went to your php page without submitting the form, so php wont know what do you mean by $name = $_POST['name'];

Now, the last thing is, how to use the serialized data :

<?php

    if(isset($_POST['data_name'])){

        $get = explode('&', $_POST['data_name'] ); // explode with and

        foreach ( $get as $key => $value) {
            $valn[ substr( $value, 0 , strpos( $value, '=' ) ) ] =  substr( $value, strpos( 
            $value, '=' ) + 1 ) ;
        }
        // access your query param
        $name = $valn['name'];
        $email = $valn['email'];
        $password = $valn['password'];
        $cnfpassword = $valn['cnfpassword'];

    }

?>

As per your javascript if your result is String('success') then only alert will call. but in your php code you echo output multiple times while connection established and after execute query.So your alert() not working due to ajax response not match your condition.