loadAsync method
Implementation
@override
loadAsync(url, [Function? onProgress]) async {
var loader = FileLoader(manager);
loader.setPath(path);
loader.responseType = responseType;
loader.setRequestHeader(requestHeader);
loader.setWithCredentials(withCredentials);
var text = await loader.loadAsync(url);
var jsonData = convert.jsonDecode(text);
return parse(jsonData);
}