XmlHttpRequest which POSTs a parameter to local server on document load and recieves a response as text.

XMLHTTPRequest.js

let request = new XMLHttpRequest();
    request.responseType = 'text';
    document.onload = function () {
        if (request.status === 200 && request.readyState === XMLHttpRequest.DONE) {
            console.log(request.responseText)
        }
        else console.log(request);
    };
    request.open('POST', 'http://localhost:4700', true);
    request.send('param');