Element: keydown event

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规范
浏览器兼容性
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keydown event is fired when a key is pressed.

不像 keypress event, the keydown event is fired for all keys, regardless of whether they produce a character value.

冒泡	Yes
可取消	Yes
接口	`KeyboardEvent`
事件处理程序特性	`onkeydown`

keydown and keyup events provide a code indicating which key is pressed, while keypress indicates which character was entered. For example, a lowercase "a" will be reported as 65 by keydown and keyup , but as 97 by keypress . An uppercase "A" is reported as 65 by all events.

Keyboard events are only generated by <inputs> , <textarea> and anything with the contentEditable attribute or with tabindex="-1" .

Since Firefox 65, the keydown and keyup events are now fired during IME composition, to improve cross-browser compatibility for CJKT users ( bug 354358 , also see keydown and keyup events are now fired during IME composition for more useful details). To ignore all keydown events that are part of composition, do something like this (229 is a special value set for a keyCode relating to an event that has been processed by an IME):

eventTarget.addEventListener("keydown", event => {
  if (event.isComposing || event.keyCode === 229) {
    return;
  }
  // do something
});

范例

addEventListener keydown example

This example logs the KeyboardEvent.code value whenever you press down a key inside the <input> 元素。

<input placeholder="Click here, then press down a key." size="40">
<p id="log"></p>

const input = document.querySelector('input');
const log = document.getElementById('log');
input.addEventListener('keydown', logKey);
function logKey(e) {
  log.textContent += ` ${e.code}`;
}

onkeydown equivalent

input.onkeydown = logKey;

规范

规范	状态
UI Events	工作草案

浏览器兼容性

更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`keydown` event	Chrome Yes	Edge ≤18	Firefox Yes	IE ?	Opera ?	Safari ?	WebView Android Yes	Chrome Android Yes	Firefox Android Yes	Opera Android ?	Safari iOS ?	Samsung Internet Android Yes

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范例

addEventListener keydown example

onkeydown equivalent

规范

浏览器兼容性

图例

另请参阅

元数据

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