如何在Internet Explorer中触发script.onerror？ [英] How to trigger script.onerror in Internet Explorer?

问题描述

MSDN上的 onerror页面声明可以将onerror处理程序附加到脚本元素，并且在对象加载期间发生错误时触发。。

The onerror page on MSDN states that the onerror handler can be attached to a script element and that it "Fires when an error occurs during object loading.".

出于单元测试的目的，我是试图让这个onerror处理程序触发，但找不到合适的例子。

For the purpose of unit tests, I am trying to get this onerror handler to fire, but could not find a suitable example.

以下代码在Firefox中触发错误，但在Internet Explorer中没有显示警告

The following code triggers an error in Firefox, but no alert is displayed in Internet Explorer

<script src="http://www.google.com/NOTFOUND.js" onerror="alert('error fired')"></script>

有没有人知道script.src的值会触发附加到script.onerror的处理程序？

Does anyone know a value for script.src that would fire the handler attached to script.onerror?

推荐答案

我发现这是隐藏在一些MSDN文档中：

请注意，文档错误地说这适用于元素太;该错误将在3月份Internet Explorer 5最终版本的Workshop文档中修复。

Note that the documentation mistakenly says this works for elements too; the error will be fixed in the Workshop documentation for the final release of Internet Explorer 5 in March.

我接下来想到的是可能有帮助的是onreadystatechange事件：

The next thing I thought of that could help is the onreadystatechange event:

<script src="http://www.google.com/NOTFOUND.js" onreadystatechange="alert(this.readyState)">

这个事件对我来说是两次，一次是加载而另一次是加载，无论是脚本是否有效。我发现的其他文档说，有时它会触发一个完整的事件，并且它应该解雇的时间并不是很清楚。所以它看起来不会起作用。

This event fires twice for me, once with "loading" and again with "loaded", whether the script is valid or not. Other documentation I've found says that sometimes it fires a complete event, and it's not really clear when it's supposed to fire. So it looks like that won't work.

所以我认为你留下了一个hacky解决方案，检查脚本应该声明的变量是否确实存在。在HTML中：

So I think you're left with the hacky solution of checking that a variable which the script is supposed to declare really exists. In HTML:

<script src="http://yourdomain.com/declare_foo.js"></script>
<script>if (typeof foo == "undefined") {alert ('error loading script');}</script>

然后当然在declare_foo.js中，你有

And then of course in declare_foo.js, you'd have

var foo = 'Script loaded successfully';

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