Ajax POST

function newPost(url, data, success) {
    fetch(url, {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json;charset=UTF-8',
            },
            body: JSON.stringify(data),
            credentials: 'include'
        }).then(res => res.text())
        .then(text => {
            if (success) {
                success(text)
            }
        });
}

function oldPost(url,data, success){
    var async2 = true;
    var method = "POST";
    var xmlhttp = new XMLHttpRequest();
    xmlhttp.onreadystatechange = function() {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
            var text = xmlhttp.responseText;
            if(success){
                success(text)
            }
        }
    }
    xmlhttp.open(method, url, async2);
    xmlhttp.setRequestHeader("Content-type", "application/json;charset=UTF-8");
    xmlhttp.send(JSON.stringify(data));
}