1

我有一个<core-icon>元素

<polymer-element name="app-element">
  <template>
    <core-icon icon="{{icon}}"></core-icon>
  </template>
  <script ...>
</polymer-element>

@CustomTag('app-element')
class AppElement extends PolymerElement {
  AppElement.created() : super.created();

  @observable
  String icon = 'menu';

  clickHandler(e) {
    icon = null;
  }
}

这导致了这个异常

Exception caught during observer callback: TypeError: Cannot read property 'split' of null
    at core-icon.Polymer.updateAlt (http://localhost:63342/core-elements/packages/core_elements/src/core-icon/core-icon.html:188:50)
    at core-icon.Polymer.updateIcon (http://localhost:63342/core-elements/packages/core_elements/src/core-icon/core-icon.html:147:14)
    at core-icon.g.invokeMethod (http://localhost:63342/core-elements/packages/polymer/src/js/polymer/polymer.js:13:25932)
    at core-icon.g.notifyPropertyChanges (http://localhost:63342/core-elements/packages/polymer/src/js/polymer/polymer.js:13:24037)
    at Object.x.report_ (http://localhost:63342/core-elements/packages/polymer/src/js/polymer/polymer.js:12:18274)
    at Object.S.check_ (http://localhost:63342/core-elements/packages/polymer/src/js/polymer/polymer.js:12:22612)
    at c (http://localhost:63342/core-elements/packages/polymer/src/js/polymer/polymer.js:12:12181) polymer.concat.js:4861x.report_ polymer.concat.js:4861S.check_ polymer.concat.js:5264c

在我看来，这是一个<core-icon>问题，我将提出一个问题，但无论如何我的问题是：

有没有办法在 Dart 中捕获这样的 JavaScript 异常？

我当然试图icon = null;用成功try/catch或失败来换行window.onError.listen((e)...);。

4

1 回答 1

0

我实际上没有尝试过，但我想这是解决方案：

来源：https ://github.com/dart-lang/core-elements/issues/148#issuecomment-62574668

看起来实际的问题是异常在 js 端被捕获然后打印到控制台，所以这就是我们无法访问它的原因。他们确实将 Observer._errorThrownDuringCallback 设置为 true，因此您可以在测试中添加以下内容，它会相应地失败：

expect(context['Observer']['_errorThrownDuringCallback'], false,
    reason: 'Setting icon to null shouldn\'t throw an error.');
于 2015-02-21T11:15:36.273 回答