Ako môžem zavolať funkciu javascript vo vnútri ajax volania

AJAX, JAVASCRIPT FUNKCIE VOLANIA

function ajaxGetRequest(path, callback){
  let request = new XMLHttpRequest();
  request.onreadystatechange = function(){
    if (this.readyState === 4 && this.status === 200){
        callback(this.response);
    }
  };
  request.open("GET", path);
  request.send();
}

function ajaxPostRequest(path, data, callback){
  let request = new XMLHttpRequest();
  request.onreadystatechange = function(){
    if (this.readyState === 4 && this.status === 200){
      callback(this.response);
    }
  };
  request.open("POST", path);
  request.send(data);
}