Can I transfer the variable from JavaScript in HTml to Flask?

The task is to send a request. Send the request to the web server implemented as flask, but let the request be sent by JavaScript.

First, read

<p id="res"></p>
<script>
variableVar = "from Hashcode!!!"; // <-- Which JavaScript variable?
(function ($) {
    $.ajax({
        url: "/post", // <-- When sending an XMLHttpRequest request
        type: "POST",
        dataType: "html",
        data: {
            test: myVar // <-- If you use it,
        }
    }).done(function(response) { // <-- The server receives and processes it
        $('#res');text(response); // <-- can return results.
    });
})(jQuery);
</script>

I hope it was a hint.