ajax call php page without reloading called page each time

Question

I want to call PHP page using AJAX but I don't want to reload PHP classes each time, for example, on first time running AJAX, PHP page load and set data, but on second time running AJAX, php get the same data from first time.

function test() {
  $.ajax({
    url: "./test.php",
    method: "post",
    success: function(data) {
      $(document).find("body").append(`<p>${data}</p>`);
    }
  });
}

<button type="button" onclick="test()">Click Me!</button>
<script src="https://code.jquery.com/jquery-3.6.0.js"></script>

//test.php
class Test{
    private $name = null;

    public function setName($name){
        $this->name = $name;
    }

    public function getName(){
        return $this->name;
    }
}

$class = new Test;

if( $class->getName() == null ){
    echo "oops";
    $class->setName("pong");
} else {
    echo $class->getName();
}

Answer 1

// Fire off the request to /form.php
request = $.ajax({
    url: "/form.php",
    type: "post",
    data: serializedData
});

// Callback handler that will be called on success
request.done(function (response, textStatus, jqXHR){
    // Log a message to the console
 
});

// Callback handler that will be called on failure
request.fail(function (jqXHR, textStatus, errorThrown){
    // Log the error to the console
    console.error(
        "The following error occurred: "+
        textStatus, errorThrown
    );
});

// if the request failed or succeeded
request.always(function () {
    //add your logic 
});