function makeCall(btn) {
    let makePost = new XMLHttpRequest();
    postData = { "button": btn };
    makePost.onreadystatechange = function () {
        if (makePost.readyState === 4) {
            document.getElementById("content").innerHTML = makePost.response;
        }
    }
    makePost.open("POST", window.location.href, true);
    makePost.send(JSON.stringify(postData));
}