keydown

Overview Table

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

<script type="text/javascript">
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>

View live example

Notes

Remarks

You can cancel all keys that fire the onkeydown event in HTML Applications, including most accelerator keys, such as ALT+F4. As of Microsoft 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, this event can be canceled for the following keys and key combinations by specifying event.returnValue=false:

• Editing: BACKSPACE, DELETE
• Letters: A - Z (uppercase and lowercase)
• Navigation: PAGE UP, PAGE DOWN, END, HOME, LEFT ARROW, RIGHT ARROW, UP ARROW, DOWN ARROW
• Numerals: 0 - 9
• Symbols: ! @ # $ % ^ & * ( ) _ - + = < [ ] { } , . / ? \ | ' ` " ~
• System: SPACEBAR, ESC, TAB, SHIFT+TAB

As of Microsoft Internet Explorer 4.0, the onkeydown event fires for the following keys:

• Editing: DELETE, INSERT
• Function: F1 - F12
• Letters: A - Z (uppercase and lowercase)
• Navigation: HOME, END, LEFT ARROW, RIGHT ARROW, UP ARROW, DOWN ARROW
• Numerals: 0 - 9
• Symbols: ! @ # $ % ^ & * ( ) _ - + = < [ ] { } , . / ? \ | ' ` " ~
• System: ESC, SPACEBAR, SHIFT, TAB

In Internet Explorer 4.0, you cannot cancel the onkeydown event, but you can use the onkeypress event to cancel keyboard events. Returns a number specifying the keyCode of the key that was pressed. To invoke this event, do one of the following:

• Press any keyboard key.

Syntax

Standards information

• HTML 4.01 Specification, Section 18.2.3

Event handler parameters

pEvtObj [in]

Type: ****IHTMLEventObj****

Attributions

• Microsoft Developer Network: [Windows Internet Explorer API reference Article]