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keydown

The keydown event is fired when a key is pressed down. Unlike the keypress event, the keydown event is fired for keys that produce a character value and for keys that do not produce a character value.

General info

Specification: DOM L3
Interface: KeyboardEvent
Bubbles: Yes
Cancelable: Yes
Target: Document, Element
Default Action: Varies: keypress event; launch text composition system; blur and focus events; DOMActivate event; other event

Properties

Property	Type	Description
`target` Read only	EventTarget	The event target (the topmost target in the DOM tree).
`type` Read only	DOMString	The type of event.
`bubbles` Read only	Boolean	Whether the event normally bubbles or not
`cancelable` Read only	Boolean	Whether the event is cancellable or not?
`view` Read only	WindowProxy	`document.defaultView` (`window` of the document)
`detail` Read only	`long` (`float`)	0.
`target` Read only	EventTarget (DOM element)	Focused element processing the key event, root element if no suitable input element focused.
`char` Read only	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` Read only	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 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.
`code` Read only	DOMString (string)	Holds a string that identifies the physical key being pressed. The value is not affected by the current keyboard layout or modifier state, so a particular key will always return the same value.
`charCode` Read only	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` Read only	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 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` Read only	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` Read only	long (float)	The location of the key on the device.
`repeat` Read only	boolean	`true` if a key has been depressed long enough to trigger key repetition, otherwise `false`.
`locale` Read only	string	The language code for the key event, if available; otherwise, the empty string.
`ctrlKey` Read only	boolean	`true` if the control key was down when the event was fired. `false` otherwise.
`shiftKey` Read only	boolean	`true` if the shift key was down when the event was fired. `false` otherwise.
`altKey` Read only	boolean	`true` if the alt key was down when the event was fired. `false` otherwise.
`metaKey` Read only	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.

Related Events

Example

<!DOCTYPE html>
<html>
<head>
<script>

'use strict';

document.addEventListener('keydown', (event) => {
  const keyName = event.key;
  alert('keydown event\n\n' + 'key: ' + keyName);
});

</script>
</head>
<body>
</body>
</html>

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