Question

我如何使用＆＃34;未来＆＃34;在客户端？

而且，我怎么能阻止我的代码的执行，而没有事件被捕获？

import 'dart:html';
import 'dart:convert';
import 'dart:async';

Map data;

Future<String> ft_get_pseudo()
{
  InputElement button;
  InputElement text;

  text = querySelector('[name="pseudo"]');
  button = querySelector('[name="push"]');
  button.onClick.listen((_) => text.value);
}

void    main()
{
    WebSocket wss;
  String encode;

  data = new Map();
    wss = new WebSocket('ws://127.0.0.1:4040/ws');
  ft_get_pseudo().then((name)
  {
    data['pseudo'] = name;
    encode = JSON.encode(data);
    wss.onOpen.listen((_) => wss.send(encode));
    wss.onMessage.listen((msg) => print("Msg received : ${msg.data}"));
  });
}

我在ecmascript 6中看到了Promise函数，有一种方法可以使用它，还是想法？

HTML：

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <script type="application/dart" src="client.dart"></script>
    <link rel="stylesheet" href="style.css" type="text/css">
    <title>Client</title>
</head>
<body>
<div id="console">
</div>
<input type="text" name="pseudo" size="20" placeholder="pseudo">
<input type="button" name="push" value="Send">
</body>
</html>

Answer 1

如果我理解正确，你想在按下按钮时从ft_get_pseudo（）函数获取text.value，对吧？如果是这样，您需要创建一个new Completer并在ft_get_pseudo（）的末尾返回其Future。然后，在按钮的onClick事件中，您只需使用text.value的值完成未来。

代码可能是这样的：

Future<String> ft_get_pseudo()
{
  Completer _completer = new Completer();

  InputElement button;
  InputElement text;

  text = querySelector('[name="pseudo"]');
  button = querySelector('[name="push"]');
  button.onClick.listen((_) => _completer.complete(text.value));

  return _completer.future;
}

Answer 2

对于这样一个简单的用例，你可以这样做

Future<String> ft_get_pseudo()
{
  return new Future(() {
    InputElement button;
    InputElement text;

    text = querySelector('[name="pseudo"]');
    button = querySelector('[name="push"]');
    button.onClick.listen((_) => _completer.complete(text.value));
  }
}

Answer 3

我想你想做这样的事情，但我还没有完全理解你想要完成的事情。您能否以不同的方式添加评论？

Map data;

void main() {
  //(querySelector('[name="push"]') as ButtonInputElement).onClick.listen(btnClickHandler);
  (querySelector('[name="push"]') as ButtonInputElement).onClick.first.then(btnClickHandler);

  // this would work too, because every element has the click event.
  // querySelector('[name="push"]').onClick.listen(btnClickHandler);
}

void btnClickHandler(MouseEvent e) {
  String name = (querySelector('[name="pseudo"]') as TextInputElement).value;    

  data = {'pseudo': name}; 
  String encode = JSON.encode(data);

  WebSocket wss = new WebSocket('ws://127.0.0.1:4040/ws');
  wss.onOpen.listen((_) => wss.send(encode));
  wss.onMessage.listen((msg) => print("Msg received : ${msg.data}"));
}

客户端，然后（）或其他？

3 个答案: