code: function preloadJSON(data, onload, onerror) {
              var xmlhttp = new XMLHttpRequest();
  
              if (xmlhttp.overrideMimeType) {
                  xmlhttp.overrideMimeType("application/json");
              }
  
              xmlhttp.open("GET", data.src + api.nocache, true);
              xmlhttp.withCredentials = me.loader.withCredentials;
  
              // set the callbacks
              xmlhttp.ontimeout = onerror;
              xmlhttp.onreadystatechange = function () {
                  if (xmlhttp.readyState === 4) {
                      // status = 0 when file protocol is used, or cross-domain origin,
                      // (With Chrome use "--allow-file-access-from-files --disable-web-security")
                      if ((xmlhttp.status === 200) || ((xmlhttp.status === 0) && xmlhttp.responseText)) {
                          // get the Texture Packer Atlas content
                          jsonList[data.name] = JSON.parse(xmlhttp.responseText);
                          // fire the callback
                          onload();
                      }
                      else {
                          onerror(data.name);
                      }
                  }
              };
              // send the request
              xmlhttp.send();
          }
docs: preload JSON files
  @ignore