var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
        var response = xhr.responseText;
        var res = JSON.parse(response);
        console.log(res.dolgozok)
    }
}    
xhr.open("GET", "valami.json", true);
xhr.send();