当一个键被按下后会触发keydown 事件
General info
- Specification
- DOM L3
- Interface
- KeyboardEvent
- Bubbles
- Yes
- Cancelable
- Yes
- Target
- Document, Element
- Default Action
- Varies:
keypressevent; launch text composition system;blurandfocusevents;DOMActivateevent; other event
Properties
| Property | Type | Description |
|---|---|---|
target 只读 |
EventTarget |
Focused element processing the key event, root element if no suitable input element focused. |
type 只读 |
DOMString |
The type of event. |
bubbles 只读 |
Boolean |
Whether the event normally bubbles or not |
cancelable 只读 |
Boolean |
Whether the event is cancellable or not? |
view 只读 |
WindowProxy |
document.defaultView (window of the document) |
detail 只读 |
long (float) |
0. |
target |
EventTarget (DOM element) | Focused element processing the key event, root element if no suitable input element focused. |
char 只读 未实现 (查看 bug 680830) |
DOMString (string) |
The character value of the key.
If the key corresponds to a printable character, this value is a non-empty Unicode string containing that character.
If the key doesn't have a printable representation, this is an empty string.
See key names and char values for the detail.
Note: If the key is used as a macro that inserts multiple characters, this attribute's value is the entire string, not just the first character.
|
key 未实现 (查看 bug 680830) |
DOMString (string) |
The key value of the key represented by the event.
If the value has a printed representation, this attribute's value is the same as the char attribute.
Otherwise, it's one of the key value strings specified in {{ anch("Key values") }}.
If the key can't be identified, this is the string "Unidentified".
See key names and char values for the detail.
Read Only.
|
charCode 只读 |
Unsigned long (int) |
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.
Warning: This attribute is deprecated; you should use
char instead, if available.
|
keyCode 只读 |
Unsigned long (int) |
A system and implementation dependent numerical code identifying the unmodified value of the pressed key.
This is usually the decimal ASCII ({{ RFC(20) }}) or Windows 1252 code corresponding to the key; see {{ anch("Virtual key codes") }} for a list of common values.
If the key can't be identified, this value is 0.
Warning: This attribute is deprecated; you should use
key instead, if available.
|
which 只读 |
Unsigned long (int) |
A system and implementation dependent numeric code identifying the unmodified value of the pressed key; this is usually the same as keyCode.
Warning: This attribute is deprecated; you should use
key instead, if available.
|
location 只读 |
long (float) | The location of the key on the device. |
repeat 只读 未实现 |
boolean |
true if a key has been depressed long enough to trigger key repetition, otherwise false.
|
locale 只读 未实现 |
string | The language code for the key event, if available; otherwise, the empty string. |
ctrlKey 只读 |
boolean | true if the control key was down when the event was fired. false otherwise. |
shiftKey 只读 |
boolean | true if the shift key was down when the event was fired. false otherwise. |
altKey 只读 |
boolean | true if the alt key was down when the event was fired. false otherwise. |
metaKey 只读 |
boolean | true if the meta key was down when the event was fired. false otherwise. |
preventDefault() of keydown event
Starting with Gecko 25, a call of preventDefault() of keydown event prevents to dispatch following keypress event. This is valid behavior for D3E spec and the other major web browsers behave this way. On the other hand, Gecko 24 or earlier dispatched keypress event even if preventDefault() of preceding keydown event is called. Although the keypress event's defaultPrevented attribute was true in this case.