Я бы рекомендовал использовать API извлечения вместо объекта XMLHttpRequest.
function postData(url = `UR_URL_HERE`, data = {}) {
// Default options are marked with *
return fetch(url, {
method: "POST", // *GET, POST, PUT, DELETE, etc.
mode: "cors", // no-cors, cors, *same-origin
cache: "no-cache", // *default, no-cache, reload, force-cache, only-if-cached
credentials: "same-origin", // include, *same-origin, omit
headers: {
"Content-Type": "application/json",
// "Content-Type": "application/x-www-form-urlencoded",
},
redirect: "follow", // manual, *follow, error
referrer: "no-referrer", // no-referrer, *client
body: JSON.stringify(data), // body data type must match "Content-Type" header
})
.then(response => response.json()); // parses response to JSON
}