onkeydown Event

Fires when the user presses a key.

Syntax

Inline HTML	<ELEMENT onkeydown = "handler" ... >	All platforms
Event property	object.onkeydown = handler	JScript (compatible with ECMA 262 language specification) only
Named script	<SCRIPT FOR = object EVENT = onkeydown>	Internet Explorer only

Remarks

Bubbles	Yes
Cancels	Yes
To invoke	Press any keyboard key.
Default action	Returns a number specifying the keyCode of the key that was pressed.

In Microsoft® Internet Explorer 4.0, the onkeydown event fires for the following keys:

• Editing: DELETE, INSERT
• Function: F1 - F12
• Letters: a - z
• Navigation: HOME, END, Left Arrow, Right Arrow, Up Arrow, Down Arrow
• Numerals: 0 - 9
• Symbols: ! @ # $ % ^ & * ( ) _ - + = < > [ ] { } , . / ? \ | ' ` " ~
• System: ESCAPE, SPACE, SHIFT, TAB

In Internet Explorer 5, the event also fires for the following keys:

• Editing: BACKSPACE
• Navigation: PAGE UP, PAGE DOWN
• System: SHIFT+TAB

As of Internet Explorer 5, the following keys and key combinations can be canceled by specifying event.returnValue=false:

• Editing: BACKSPACE, DELETE
• Letters: a - z
• Navigation: PAGE UP, PAGE DOWN, END, HOME, Left Arrow, Right Arrow, Up Arrow, Down Arrow
• Numerals: 0 - 9
• Symbols: ! @ # $ % ^ & * ( ) _ - + = < > [ ] { } , . / ? \ | ' ` " ~
• System: SPACE, ESCAPE, TAB, SHIFT+TAB

You can cancel all keys that fire the onkeydown event in HTML Applications, including most accelerator keys, such as ALT+F4.

In Internet Explorer 4.0, you cannot cancel the onkeydown event, but you can use the onkeypress event to cancel keyboard events.

Event Object Properties

Although event handlers in the DHTML Object Model do not receive parameters directly, the handler can query the event object for data.

Event Object Properties

altKey	Retrieves the current state of the ALT key.
cancelBubble	Sets or retrieves whether the current event should bubble up the hierarchy of event handlers.
clientX	Retrieves the x-coordinate of the mouse cursor relative to the client area of the window, excluding window decorations or scroll bars.
clientY	Retrieves the y-coordinate of the mouse cursor relative to the client area of the window, excluding window decorations or scroll bars.
ctrlKey	Retrieves the state of the CTRL key.
keyCode	Sets or retrieves the Unicode key code associated with the key that caused the event.
offsetX	Retrieves the horizontal coordinate of the mouse's position relative to the object firing the event.
offsetY	Retrieves the vertical coordinate of the mouse's position relative to the object firing the event.
repeat	Retrieves whether an event is being repeated.
returnValue	Sets or retrieves the return value from the event.
screenX	Retrieves the horizontal position of the mouse, in pixels, relative to the user's screen.
screenY	Retrieves the vertical position of the mouse, in pixels, relative to the user's screen.
shiftKey	Retrieves the state of the SHIFT key.
srcElement	Retrieves the object that fired the event.
type	Retrieves the event name from the event object.
x	Retrieves the x-coordinate of the mouse cursor relative to the parent element.
y	Retrieves the y-coordinate of the mouse cursor relative to the parent element.

Example

This example uses the onkeydown event to cancel input from the keyboard.

<SCRIPT>
function fnTrapKD(){
   if(oTrap.checked){
      oOutput.innerText+="[trap = " + event.keyCode + "]";
      event.returnValue=false;
   }
   else{
      oOutput.innerText+=String.fromCharCode(event.keyCode);
   }
}
</SCRIPT>
<INPUT TYPE="checkbox" ID="oTrap">
<INPUT ID="oExample" TYPE="text" onkeydown="fnTrapKD()">
<TEXTAREA ID="oOutput" ROWS="10" COLS="50">
</TEXTAREA>

This feature requires Internet Explorer 5 or later. Click the icon below to install the latest version. Then reload this page to view the sample.

Applies To

[ Object Name ] Platform Version Win16: Win32: Mac: Unix: WinCE: Version data is listed when the mouse hovers over a link, or the link has focus.

A, ACRONYM, ADDRESS, APPLET, AREA, B, BDO, BIG, BLOCKQUOTE, BODY, BUTTON, CAPTION, CENTER, CITE, CODE, custom, DD, DEL, DFN, DIR, DIV, document, DT, EM, FIELDSET, FONT, FORM, Hn, HR, I, INPUT type=button, INPUT type=checkbox, INPUT type=file, INPUT type=image, INPUT type=password, INPUT type=radio, INPUT type=reset, INPUT type=submit, INPUT type=text, KBD, LABEL, LEGEND, LI, LISTING, MAP, MARQUEE, MENU, NEXTID, NOBR, OBJECT, OL, P, PLAINTEXT, PRE, Q, RT, RUBY, S, SAMP, SELECT, SMALL, SPAN, STRIKE, STRONG, SUB, SUP, TABLE, TBODY, TD, TEXTAREA, TFOOT, TH, THEAD, TR, TT, U, UL, VAR, XMP

See Also

onkeyup