javascript 在 Chrome 扩展内容脚本中，我是否必须在处理文档之前等待 document.ready？
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In a Chrome Extension content script, must I wait for document.ready before processing the document?
提问by David Mills
Specifically, I'm evaluating all of the images on a page to see if they have a certain attribute, and then adding some new <divs> to the DOM based on those attributes. Must I wait for document.ready to fire before performing these modifications in order to be guaranteed that Chrome has loaded all of the necessary pieces of the DOM?
具体来说，我正在评估页面上的所有图像以查看它们是否具有某个属性，然后根据这些属性将一些新的 <divs> 添加到 DOM。在执行这些修改之前，我是否必须等待 document.ready 触发才能保证 Chrome 已经加载了 DOM 的所有必要部分？
The problem I'm running into is that sometimes document.ready takes a short while to fire and the user is already browsing around the page, wondering why my extension hasn't yet had any effect. The problem usually only lasts a moment, but it's enough to be annoying.
我遇到的问题是有时 document.ready 需要很短的时间才能触发，而用户已经在浏览页面，想知道为什么我的扩展程序还没有产生任何效果。问题通常只持续片刻，但足以令人讨厌。
If I don't bother waiting for document.ready, and instead immediately process the document, everything seemsto work; but I wonder if I'm just getting lucky.
如果我不费心等待 document.ready，而是立即处理文档，一切似乎都正常；但我想知道我是否只是走运了。
回答by Mohamed Mansour
Actually, you don't have to wait. You can process right away in Content Scripts. Just make sure you don't use document_startin the run_atattribute.
实际上，您不必等待。您可以立即在Content Scripts 中进行处理。只要确保你不使用document_start的run_at属性。
In document_end, the files are injected immediately after the DOM is complete, but before subresources like images and frames have loaded. document_idle(the default value) happens even later.
在 中document_end，文件在 DOM 完成后立即注入，但在图像和帧等子资源加载之前。document_idle（默认值）发生得更晚。
{
"name": "My extension",
...
"content_scripts": [
{
"matches": ["http://www.google.com/*"],
"css": ["mystyles.css"],
"js": ["jquery.js", "myscript.js"],
"run_at": "document_end"
}
],
...
}
回答by thinkdevcode
Short answer: yes.
简短的回答：是的。
Long answer: jQuery won't be able to grab any DOM elements that aren't already rendered. I know i've gotten into trouble a few times and it can be quite annoying to debug something for awhile and then realize I forgot to wrap the code in a document.ready. If its working for you, it's because your lucky. Also, you dont need to wrap it in a document.ready if your scripts are at the bottom of your page, just above your closing body tag.
长答案：jQuery 将无法获取任何尚未呈现的 DOM 元素。我知道我遇到了几次麻烦，调试一段时间后发现我忘记将代码包装在 document.ready 中可能会很烦人。如果它对你有用，那是因为你很幸运。此外，如果您的脚本位于页面底部，就在结束正文标记的上方，则无需将其包装在 document.ready 中。
