KeyboardEvent

Objetos do tipo KeyboardEvent descrevem a interação do usuário com o teclado. Cada evento descreve uma tecla; o tipo de evento (keydown, keypress, ou keyup) identifica qual tipo de ação foi executada.

Construtor

KeyboardEvent()

Cria um objeto do tipo KeyboardEvent.

Métodos

Essa interface também herda métodos dos seus pais, UIEvent e Event.

KeyboardEvent.getModifierState()

Retorna um Boolean indicando se uma tecla, como Alt, Shift, Ctrl, ou Meta, foi pressionada quando o evento foi criado.

KeyboardEvent.initKeyEvent()

Inicializa um objeto do tipo KeyboardEvent . isso foi apenas implementado por Gecko (outros usaram KeyboardEvent.initKeyboardEvent()) e não deve mais ser usado. A forma moderna padrão é usar o construtor KeyboardEvent().

KeyboardEvent.initKeyboardEvent()

Inicializa um objeto do tipo KeyboardEvent . Isso nunca foi implementado por Gecko (que usou KeyboardEvent.initKeyEvent()) e não deve mais ser usado. A forma moderna padrão é usar o construtor  KeyboardEvent().

Propriedades

Essa interface também herda métodos dos seus pais, UIEvent e Event.

KeyboardEvent.altKey Somente leitura

Retorna um Boolean que é true se a tecla Alt ( Option ou ⌥ no OS X) estava ativa quando o evento foi acionado.

KeyboardEvent.char Somente leitura

Retorna um DOMString representando o valor da tecla em caractere. Se a tecla corresponde a um caractere exibível, esse valor é uma string Unicode não-vazia contendo aquele caractere. Se a tecla não possui uma representação exibível, ela é uma string vazia.

Nota: Se a tecla é usada como um macro que insere caracteres múltiplos, o valor desse atributo é a string inteira, não apenas o primeiro caractere.

Aviso: Isso foi removido dos Eventos DOM de nível 3. Isso é apenas suportado no IE.

KeyboardEvent.charCode Somente leitura

Returns a Number representing the Unicode reference number of the key; this attribute is used only by the 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.

Aviso: Este atributo esta depreciado; você deve usar key no lugar, se disponivel.

KeyboardEvent.code Somente leitura

Returns a DOMString with the code value of the key represented by the event.

KeyboardEvent.ctrlKey Somente leitura

Returns a Boolean that is true if the Ctrl key was active when the key event was generated.

KeyboardEvent.isComposing Somente leitura

Returns a Boolean that is true if the event is fired between after compositionstart and before compositionend.

KeyboardEvent.key Somente leitura

Returns a DOMString representing the key value of the key represented by the event.

KeyboardEvent.keyCode  Somente leitura

Returns a Number representing a system and implementation dependent numerical code identifying the unmodified value of the pressed key.

Aviso: Este atributo esta depreciado; você deve usar key no lugar, se disponivel.

KeyboardEvent.locale Somente leitura

Returns a DOMString representing a locale string indicating the locale the keyboard is configured for. This may be the empty string if the browser or device doesn't know the keyboard's locale.

Note: This does not describe the locale of the data being entered. A user may be using one keyboard layout while typing text in a different language.

KeyboardEvent.location Somente leitura

Returns a Number representing the location of the key on the keyboard or other input device.

KeyboardEvent.metaKey Somente leitura

Returns a Boolean that is true if the Meta (or Command on OS X) key was active when the key event was generated.

KeyboardEvent.repeat Somente leitura

Returns a Boolean that is true if the key is being held down such that it is automatically repeating.

KeyboardEvent.shiftKey Somente leitura

Returns a Boolean that is true if the Shift key was active when the key event was generated.

KeyboardEvent.which Somente leitura

Returns a Number representing a system and implementation dependent numeric code identifying the unmodified value of the pressed key; this is usually the same as keyCode.

Aviso: Este atributo esta depreciado; você deve usar key no lugar, se disponivel.

Notes

There are keydown, keypress, and keyup events. For most keys, Gecko dispatches a sequence of key events like this:

1. When the key is first depressed, the keydown event is sent.
2. If the key is not a modifier key, the keypress event is sent.
3. When the user releases the key, the keyup event is sent.

Special cases

Certain keys toggle the state of an LED indicator, such as Caps Lock, Num Lock, and Scroll Lock. On Windows and Linux, these keys dispatch only the keydown and keyup events. Note that on Linux, Firefox 12 and earlier also dispatched the keypress event for these keys.

On Mac, however, Caps Lock dispatches only the keydown event due to a platform event model limitation. Num Lock had been supported on old MacBook (2007 model and older) but Mac hasn't supported Num Lock feature even on external keyboards in these days. On the old MacBook which has Num Lock key, Num Lock doesn't cause any key events. And Gecko supports Scroll Lock key if an external keyboard which has F14 is connected. However, it generates keypress event. This inconsistent behavior is a bug; see bug 602812.

Auto-repeat handling

When a key is pressed and held down, it begins to auto-repeat. This results in a sequence of events similar to the following being dispatched:

1. keydown
2. keypress
3. <<repeating until the user releases the key>>
4. keyup

This is what the DOM Level 3 specification says should happen. There are some caveats, however, as described below.

Auto-repeat on some GTK environments such as Ubuntu 9.4

In some GTK-based environments, auto-repeat dispatches a native key-up event automatically during auto-repeat, and there's no way for Gecko to know the difference between a repeated series of keypresses and an auto-repeat. On those platforms, then, an auto-repeat key will generate the following sequence of events:

1. keydown
2. keypress
3. <<repeating until the user releases the key>>
4. keyup

In these environments, unfortunately, there's no way for web content to tell the difference between auto-repeating keys and keys that are just being pressed repeatedly.

Auto-repeat handling prior to Gecko 4.0

Before Gecko 4.0 , keyboard handling was less consistent across platforms.

Windows

Auto-repeat behavior is the same as in Gecko 4.0 and later.

Mac

After the initial keydown event, only keypress events are sent until the keyup event occurs; the inter-spaced keydown events are not sent.

Linux

The event behavior depends on the specific platform. It will either behave like Windows or Mac depending on what the native event model does.

Example

<!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>

Specifications

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, KeyboardEvent.initKeyEvent() by Gecko browsers and the early DOM Events Level 3 version, KeyboardEvent.initKeyboardEvent() by others. Both have been superseded by the modern usage of a constructor: KeyboardEvent().

Browser compatibility

[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.