如何找出哪个 DOM 元素具有焦点? [英] How do I find out which DOM element has the focus?
问题描述
我想在 JavaScript 中找出当前具有焦点的元素.我一直在浏览 DOM，但还没有找到我需要的东西.有没有办法做到这一点，以及如何做到这一点?
I would like to find out, in JavaScript, which element currently has focus. I've been looking through the DOM and haven't found what I need, yet. Is there a way to do this, and how?
我找这个的原因:
我正在尝试使箭头和 enter 之类的键在输入元素表中导航.Tab 现在可以工作，但输入和箭头似乎默认情况下不起作用.我已经设置了关键处理部分，但现在我需要弄清楚如何在事件处理函数中移动焦点.
I'm trying to make keys like the arrows and enter navigate through a table of input elements. Tab works now, but enter, and arrows do not by default it seems. I've got the key handling part set up but now I need to figure out how to move the focus over in the event handling functions.
推荐答案
使用 document.activeElement，所有主流浏览器都支持.
Use document.activeElement, it is supported in all major browsers.
以前，如果您试图找出哪个表单字段具有焦点，则无法找到.要在旧浏览器中模拟检测，请向所有字段添加焦点"事件处理程序，并将最后一个焦点字段记录在变量中.添加模糊"处理程序以在最后聚焦的字段的模糊事件时清除变量.
Previously, if you were trying to find out what form field has focus, you could not. To emulate detection within older browsers, add a "focus" event handler to all fields and record the last-focused field in a variable. Add a "blur" handler to clear the variable upon a blur event for the last-focused field.
如果需要删除activeElement，可以使用blur；document.activeElement.blur().它会将 activeElement 更改为 body.
If you need to remove the activeElement you can use blur; document.activeElement.blur(). It will change the activeElement to body.
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