检查一个键是否已关闭?

问题描述

有没有办法检测一个键当前是否在 JavaScript 中被关闭?

Is there a way to detect if a key is currently down in JavaScript?

我知道keydown"事件，但这不是我需要的.按键被按下后的一段时间，我希望能够检测它是否仍然被按下.

I know about the "keydown" event, but that's not what I need. Some time AFTER the key is pressed, I want to be able to detect if it is still pressed down.

P.S. 最大的问题似乎是在一段时间后键开始重复，像恶魔一样触发 keydown 和 keyup 事件.希望只有一个简单的 isKeyDown(key) 函数，但如果没有，则需要克服/解决这个问题.

P. S. The biggest issue seems to be that after some period of time the key begins to repeat, firing off keydown and keyup events like a fiend. Hopefully there is just a simple isKeyDown(key) function, but if not then this issue will need to be overcome / worked around.

推荐答案

有没有办法检测一个键当前是否在 JavaScript 中被关闭?

Is there a way to detect if a key is currently down in JavaScript?

不.唯一的可能是监控每个 keyup 和 keydown 并记住.

Nope. The only possibility is monitoring each keyup and keydown and remembering.

一段时间后，按键开始重复，像恶魔一样触发 keydown 和 keyup 事件.

after some period of time the key begins to repeat, firing off keydown and keyup events like a fiend.

不应该.你肯定会得到 keypress 重复，并且在许多浏览器中你也会得到重复 keydown，但是如果 keyup 重复，这是一个错误.

It shouldn't. You'll definitely get keypress repeating, and in many browsers you'll also get repeated keydown, but if keyup repeats, it's a bug.

不幸的是，这不是一个完全闻所未闻的错误:在 Linux、Chromium 和 Firefox 上(当它在 GTK+ 下运行时，它在流行的发行版中，如 Ubuntu)都生成重复的 keyup-keypress-keydown 序列握着钥匙，这与快速敲击钥匙的人无法区分.

Unfortunately it is not a completely unheard-of bug: on Linux, Chromium, and Firefox (when it is being run under GTK+, which it is in popular distros such as Ubuntu) both generate repeating keyup-keypress-keydown sequences for held keys, which are impossible to distinguish from someone hammering the key really fast.

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