const request = {
            get: function (url, callback) {
                let xmlHttp = new XMLHttpRequest();
                xmlHttp.onreadystatechange = function() {
                    if (xmlHttp.readyState === 4 && xmlHttp.status === 200)
                        callback(xmlHttp.responseText);
                };
                xmlHttp.open("GET", url, true);
                xmlHttp.send();
            },

            post: function (url, callback, data) {
                let xmlHttp = new XMLHttpRequest();
                xmlHttp.onreadystatechange = function() {
                    if (xmlHttp.readyState === 4 && xmlHttp.status === 200)
                        callback(xmlHttp.responseText);
                };
                xmlHttp.open("POST", url, true);
                xmlHttp.send(this.formatParams(data));
            },

            formatParams: function (params) {
                return Object.keys(params).map((key) => {
                    return key+"="+encodeURIComponent(params[key])
                }).join("&")
            }
        };

function elementFromHTML(html) {
    let elem = document.createElement('div');
    elem.innerHTML = html;
    return elem.firstChild;
}