Javascript getElementById null错误 [英] Javascript getElementById null error

问题描述

我最近发布了关于firefox中javascript的一个问题，并且表示问题很可能是document.write（）以某种方式覆盖了脚本。 有人建议我使用ID来解决覆盖脚本和避免堆叠信息的问题。

I posted quite recently about an issue with javascript in firefox, and it was denoted the problem was likely document.write() overwriting the script somehow. It was suggested I use IDs to solve the problem of both overwriting the script and to avoid stacking of the information.

然而，在尝试将ID实现到我的javascript和html代码中时，我发现firebug报告：

However, on trying to implement the IDs into my javascript and html code, I found that firebug reports that:

"TypeError: document.getElementById("author_container") is null"

尽管事实如此，ID已经在以下定义：

Despite the fact, that, once again, the ID is already defined under:

<p id="author_container"></p>

并且显然没有拼写错误，并重新安排脚本头部分或改变它所以p发生在脚本完全没有区别之前。 （注意，尽管首先出现了脚本，但另一个示例运行正常。）

And there are clearly no typos, and re-arranging the script into the head section or altering it so the p occurs before the script makes absolutely no difference. (Note the other example runs fine despite the script occurring first).

如果我使用预先存在的ID和getElementById示例并在firefox中运行它，它会运行罚款：

If I use a pre-existing example of an ID and getElementById and run it in firefox, it runs fine:

http://pastebin.com/FTEX1HGE

但如果我尝试运行我的代码，这似乎没有什么大不相同，我遇到了问题：
http://pastebin.com/XfGUpZAS

But if I try to run my code, which doesn't seem that majorly different, I run into issues: http://pastebin.com/XfGUpZAS

我在这里遗漏了什么吗？如何更改代码以使其在Firefox中运行？ firefox是否允许我正确运行我的代码？ （下周查找？）

Am I missing something here? How do I alter the code to make it work in firefox? Will firefox allow me to ever run my code correctly? (Find out next week?)

推荐答案

将您的脚本放在页面底部，就在结束<$ c $之前c>< / body> 标记。换句话说，使脚本标记成为 document.body 的最后一个。这样，在脚本开始之前就完全加载了DOM树。

Place your script at the bottom of the page, right before the closing </body> tag. In other words, make the script tag the last one of document.body. That way the DOM-tree is completely loaded before the scripting starts.

除了许多问题之外，真正的问题是 document.open GenerateCoord 函数中的语句。 清除完整的文档，之后 - 确实 - 没有任何元素可以通过任何Id获取。这是没有它的 jsfiddle 。

Aside from a number of issues, the real issue is the document.open statement in the GenerateCoord function. That clears the complete document, after which - indeed - no element is left to get by any Id. Here's a jsfiddle without it.

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