I have function, that sends request to create encrypted cookie. Inside that function there is onload function.

What I need?
I need to "transfer" return from onload() to parent function.

function createCookie(method = "POST", action, parameters, token, contentType = "application/x-www-form-urlencoded") {
    let xhr = new XMLHttpRequest();
    xhr.open(method, action, true);
    xhr.setRequestHeader('Content-type', contentType);
    xhr.onload = () => {
        let jsonResponse = JSON.parse(xhr.responseText);
        if(jsonResponse && jsonResponse['status'] == 'true') {
            return true;
        } else {
            return false;
        }
    }
    xhr.send("_token=" + token + "&" + parameters);
}