getdata.js

function getData(method, url) {
  return new Promise(function(resolve, reject){
    var xhr = new XMLHttpRequest();
    xhr.open(method, url);
    xhr.onload = function() {
      if (this.status >= 200 && this.status < 300) {
        resolve(xhr.response);
      } else {
        reject({
          status: this.status;
          statusText: xhr.statusText
        });
      }
    };
    xhr.onerror = function() {
      reject({
        status: this.status;
        statusText: xhr.statusText
      }); 
    };
    xhr.send();
  });
}