{{APIRef("DOM Events")}}
KeyboardEvent objects 用來詳述使用者和網頁之間，經由鍵盤產生的互動。每個事件（event）都記錄著一次鍵盤動作。事件類型（keydown 、 keypress 和 keyup）用來表示鍵盤執行哪種動作。
KeyboardEvent 僅顯示在鍵盤上發生的事。當你需要進行文字輸入的操作，請使用 HTML5 input event 代替 KeyboardEvent 。舉例來說，當使用者在手寫系統，例如平板電腦，輸入文字時，並不會啟動 key events 。KeyboardEvent object。本介面（ interface）亦繼承其父， {{domxref("UIEvent")}} 和 {{domxref("Event")}} ，的 methods
KeyboardEvent object。這個 method 只有 Gecko 有在使用（其他瀏覽器是使用 {{domxref("KeyboardEvent.initKeyboardEvent()")}}），並且不應該再繼續使用。現代的標準規範是使用 {{domxref("KeyboardEvent.KeyboardEvent", "KeyboardEvent()")}} constructor。KeyboardEvent object。 Gecko 從未實作過該 method （Gecko 是使用 {{domxref("KeyboardEvent.initKeyEvent()")}}) ，並且不應該再繼續使用。現代的標準規範是使用 {{domxref("KeyboardEvent.KeyboardEvent", "KeyboardEvent()")}} constructor。本介面（ interface）亦繼承其父，{{domxref("UIEvent")}} 和 {{domxref("Event")}} ，的 properties 。
keypress event. For keys whose char attribute contains multiple characters, this is the Unicode value of the first character in that attribute. In Firefox 26 this returns codes for printable characters.
compositionstart 和 compositionend 之間。true if the Meta (on Mac keyboards, the ⌘ Command key; on Windows keyboards, the Windows key (⊞)) key was active when the key event was generated.true if the key is being held down such that it is automatically repeating.true if the Shift key was active when the key event was generated.keyCode.
KeyboardEvent 有 keydown 、 keypress 、 keyup 三種事件。對大多數的按鍵而言， Gecko 觸發事件的順序如下：
keydown event 。keypress event 。keyup event 。某些按鍵，例如 Caps Lock 、 Num Lock 和 Scroll Lock 能切換鍵盤上的 LED 燈。在 Windows 和 Linux 系統上，這些按鍵只會觸發 keydown 和 keyup 事件。但是 Linux 上的 Firefox 12 或更早的版本亦會觸發 keypress 事件。
而在 Mac 電腦則不同， Caps Lock 只會觸發 keydown 事件；而 Num Lock 則是只有舊版的 Mac 電腦（2007 或之前的版本）才有，現在的 Mac 即便使用外部鍵盤也不支援 Num Lock 。雖說舊版的 Mac 電腦支援 Num Lock 鍵，但 Num Lock 並不會執行任何 KeyboardEvent；而 Gecko 瀏覽器在特殊情況（外接一個有 F14 的鍵盤）下能支援 Scroll Lock ，但是它會產生 keypress 事件。這個異常狀態是個 bug ，詳情可參考 {{bug(602812)}}。
當按鍵按下去不放時，它會開始一個自動迴圈。並導致觸發一系列的相似事件，如下所示：
keydownkeypresskeydownkeypresskeyup在 DOM Level 3 說明書有提及這問題是會發生的。其中所存在的問題如下說明：
部分的 GTK-based 環境之中，自動迴圈在發生的過程中會自動觸發電腦本機的 key-up 事件。然而，對 Gecko 而言，並沒有方法可以分辨使用者重複點擊按鍵與自動迴圈（按鍵按住不放）的差異。在這類的環境下，按鍵按住不放會重複執行下列事件：
keydownkeypresskeyupkeydownkeypresskeyupkeyup不幸地，在這些環境之下，web content 亦沒有方法告訴使用者重複點擊按鍵與自動迴圈的差異。
Gecko 5.0 {{geckoRelease('5.0')}} 以前，在不同平台上，鍵盤的處理與現在相比較不統一。
<!DOCTYPE html>
<html>
<head>
<script>
var metaChar = false;
var exampleKey = 16;
function keyEvent(event) {
var key = event.keyCode || event.which;
var keychar = String.fromCharCode(key);
if (key == exampleKey) {
metaChar = true;
}
if (key != exampleKey) {
if (metaChar) {
alert("Combination of metaKey + " + keychar);
metaChar = false;
} else {
alert("Key pressed " + key);
}
}
}
function metaKeyUp (event) {
var key = event.keyCode || event.which;
if (key == exampleKey) {
metaChar = false;
}
}
</script>
</head>
<body onkeydown="keyEvent(event)" onkeyup="metaKeyUp(event)">
</body>
</html>
| Specification | Status | Comment |
|---|---|---|
| {{SpecName('DOM3 Events', '#interface-KeyboardEvent', 'KeyboardEvent')}} | {{Spec2('DOM3 Events')}} | 原始定義 |
The KeyboardEvent interface specification went through numerous draft versions, first under DOM Events Level 2 where it was dropped as no consensus arose, then under DOM Events Level 3. This led to the implementation of non-standard initialization methods, the early DOM Events Level 2 version, {{domxref("KeyboardEvent.initKeyEvent()")}} by Gecko browsers and the early DOM Events Level 3 version, {{domxref("KeyboardEvent.initKeyboardEvent()")}} by others. Both have been superseded by the modern usage of a constructor: {{domxref("KeyboardEvent.KeyboardEvent", "KeyboardEvent()")}}.
More compatibility data is available on other pages:
.code ：請參考《瀏覽器支援度》的 {{domxref("KeyboardEvent.code")}} 部分。.key：請參考《瀏覽器支援度》的 {{domxref("KeyboardEvent.key")}} 部分。.getModifierState() ：請參考《瀏覽器支援度》的 {{domxref("KeyboardEvent.getModifierState")}} 部分。{{CompatibilityTable}}
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|
| Basic support | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} |
| constructor | {{CompatVersionUnknown}} | {{CompatGeckoDesktop("31.0")}} | {{CompatNo}} | {{CompatVersionUnknown}} | {{CompatUnknown}} |
.char |
{{CompatNo}} | {{CompatNo}} | {{CompatVersionUnknown}} | {{CompatNo}} | {{CompatNo}} |
.charCode |
{{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} |
.code |
See Browser compatibility of {{domxref("KeyboardEvent.code")}}. | ||||
.isComposing |
{{CompatNo}} | {{CompatGeckoDesktop("31.0")}} | {{CompatNo}} | {{CompatNo}} | {{CompatNo}} |
.key |
See Browser compatibility of {{domxref("KeyboardEvent.key")}}. | ||||
.keyCode |
{{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} |
.locale |
{{CompatNo}} | {{CompatNo}} | {{CompatVersionUnknown}} | {{CompatNo}} | {{CompatNo}} |
.location |
{{CompatVersionUnknown}} | {{CompatGeckoDesktop("15.0")}} | {{CompatVersionUnknown}} | {{CompatNo}} | {{CompatNo}} |
.repeat |
{{CompatVersionUnknown}} | {{CompatGeckoDesktop("28.0")}} | {{CompatVersionUnknown}} | {{CompatNo}} | {{CompatNo}} |
.which |
{{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} | {{CompatVersionUnknown}} |
.getModifierState() |
See Browser compatibility of {{domxref("KeyboardEvent.getModifierState")}} | ||||
.initKeyboardEvent() |
{{CompatVersionUnknown}}[1] | {{CompatNo}}[2] | {{CompatIE("9.0")}}[3] | {{CompatUnknown}} | {{CompatVersionUnknown}}[1] |
| Feature | Android | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile | |
|---|---|---|---|---|---|---|
| Basic support | {{CompatUnknown}} | {{CompatVersionUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | |
| constructor | {{CompatUnknown}} | {{CompatGeckoMobile("31.0")}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | |
.char |
{{CompatUnknown}} | {{CompatNo}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | |
.charCode |
{{CompatUnknown}} | {{CompatVersionUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | |
.code |
See Browser compatibility of {{domxref("KeyboardEvent.code")}}. | |||||
.isComposing |
{{CompatNo}} | {{CompatGeckoMobile("31.0")}} | {{CompatNo}} | {{CompatNo}} | {{CompatNo}} | |
.key |
See Browser compatibility table of {{domxref("KeyboardEvent.key")}}. | |||||
.keyCode |
{{CompatUnknown}} | {{CompatVersionUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | |
.locale |
{{CompatUnknown}} | {{CompatNo}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | |
.location |
{{CompatUnknown}} | {{CompatGeckoMobile("15.0")}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | |
.repeat |
{{CompatUnknown}} | {{CompatGeckoMobile("28.0")}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | |
.which |
{{CompatUnknown}} | {{CompatVersionUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | |
.getModifierState() |
See Browser compatibility of {{domxref("KeyboardEvent.getModifierState")}} | |||||
.initKeyboardEvent() |
{{CompatUnknown}} | {{CompatNo}} | {{CompatUnknown}} | {{CompatUnknown}} | {{CompatUnknown}} | |
[1] The arguments of initKeyboardEvent() of WebKit and Blink's are different from the definition in DOM Level 3 Events. The method is: initKeyboardEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in views::AbstractView viewArg, in DOMString keyIndentifierArg, in number locationArg, in boolean ctrlKeyArg, in boolean altKeyArg, in boolean shiftKeyArg, in boolean metaKeyArg, in boolean altGraphKeyArg)
[2] Gecko won't support initKeyboardEvent() because supporting it completely breaks feature detection of web applications. See {{Bug(999645)}}.
[3] The argument of initKeyboardEvent() of IE is different from the definition in DOM Level 3 Events. The method is: initKeyboardEvent(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in views::AbstractView viewArg, in DOMString keyArg, in number locationArg, in DOMString modifierListArg, in boolean repeatArt, in DOMString locationArg). See document of initKeyboardEvent() in MSDN.
[4] Note that manually firing an event does not generate the default action associated with that event. For example, manually firing a key event does not cause that letter to appear in a focused text input. In the case of UI events, this is important for security reasons, as it prevents scripts from simulating user actions that interact with the browser itself.