function callback(data){console.log(data)}
get('example.com',{'foo':'bar','hoge':'hoge'},callback)

function get(url, param, callback_function){
    let Full_url = url + "?";
    let count = 0;
    for (key in param) {
        if (count++ != 0) Full_url += "&";
        Full_url += key + "=" + param[key]
    }
    let xhr = new XMLHttpRequest();
    console.log(Full_url)
    xhr.open('GET', Full_url);
    xhr.setRequestHeader('Content-Type', 'text/html');
    xhr.onreadystatechange = function () {
        if (xhr.readyState === 4) {
            if (xhr.status === 200) {
                callback_function(xhr.responseText)
            } else {
                console.log("error\nstatus = " + xhr.status);
            }
        }
    };
    xhr.send();
};