Feat timeout and custom param

lib/jsonpadding.dart

@@ -1,10 +1,17 @@
 // Copyright (c) 2016, <your name>. All rights reserved. Use of this source code
 // is governed by a BSD-style license that can be found in the LICENSE file.
-import 'src/jsonp_call.dart';
 import 'dart:async';
+import 'src/jsonp_call.dart';
 
-Future<dynamic> jsonp(dynamic uri) => new JsonpCall(uri).call();
+Future<dynamic> jsonp(dynamic uri, {String param, Duration timeout}) =>
+    new JsonpCall(uri, param: param, timeout: timeout).call();
 
 class Jsonp {
-  Future<dynamic> get(dynamic uri) => jsonp(uri);
+  final String param;
+  final Duration timeout;
+
+  Jsonp({this.param, this.timeout});
+
+  Future<dynamic> get(dynamic uri, {String param, Duration timeout}) =>
+      jsonp(uri, param: param ?? this.param, timeout: timeout ?? this.timeout);
 }

lib/src/jsonp_call.dart

@@ -1,8 +1,8 @@
 // Copyright (c) 2016, <your name>. All rights reserved. Use of this source code
 // is governed by a BSD-style license that can be found in the LICENSE file.
+import 'dart:async';
 import 'dart:html';
 import 'dart:js';
-import 'dart:async';
 
 int _requestId = 0;
 
@@ -12,31 +12,45 @@ class JsonpCall {
   final ScriptElement script = new ScriptElement();
   final String callback = _createId();
   Uri uri;
+  String _param = 'callback';
+  final Duration timeout;
+  Timer _timer;
 
-  JsonpCall(dynamic uri) {
+  JsonpCall(dynamic uri, {String param, this.timeout}) {
+    _param = param ?? _param;
     this.uri = _createUri(uri, callback);
   }
 
+  bool get hasTimeout => timeout != null;
+
   Future<dynamic> call() {
     Completer completer = new Completer();
     context[callback] = completer.complete;
     script.src = uri.toString();
     script.onError.listen((_) {
       completer.completeError('Failed to load $uri');
     });
+
     document.body.append(script);
+
+    if (hasTimeout) {
+      _timer = new Timer(timeout,
+          () => completer.completeError(new TimeoutException(null, timeout)));
+    }
+
     return completer.future.whenComplete(_cleanup);
   }
 
   void _cleanup() {
+    _timer?.cancel();
     script.remove();
     context.deleteProperty(callback);
   }
 
   Uri _createUri(dynamic uri, String callback) {
     uri = (uri is Uri) ? uri : Uri.parse(uri);
     Map parameters = new Map.from(uri.queryParameters);
-    parameters['callback'] = callback;
+    parameters[_param] = callback;
     return uri.replace(queryParameters: parameters);
   }
 }