event handler in <body> doesn't work

Chris · Nov 2, 2009

Hi.

I tried to disable the backspace-key using 2 different scenarios.
One works but the other doesn't and I don't understand why the 2nd
scenario doesn't work

Scenario 1 (working scenario)

<head>
<script language="javascript" type="text/javascript">
function DisableBackspace(e) {
// for complete code, see end of mail
}
// activating the handler here
document.onkeydown = DisableBackspace;
</script>
</head>

<body> 
</body>

but the 2nd scenario doesn't work.
why not?

thank you
Chris

Complete code:

<html>
<head>
<title></title>

<script language="javascript" type="text/javascript">
function DisableBackspace(e) {
if (!e)
e = window.event;

if (e.keyCode)
keycode = e.keyCode; // IE
else
keycode = e.which; // Firefox

if (e.keyCode == 8)
return false;
}
document.onkeydown = DisableBackspace; // uncomment
for Scenario 1
</script>

</head>
 

<body>

</body>
</html>

Martin Honnen · Nov 2, 2009

Chris said:
<body onkeydown="DisableBackspace(event);"> 
</body>

but the 2nd scenario doesn't work.
why not?

You need
<body onkeydown="return DisableBackspace(event);">

Lasse Reichstein Nielsen · Nov 2, 2009

Chris said:
I tried to disable the backspace-key using 2 different scenarios.
One works but the other doesn't and I don't understand why the 2nd
scenario doesn't work

Scenario 1 (working scenario)

<head>
<script language="javascript" type="text/javascript">

(The language attribute is unnecessary)

function DisableBackspace(e) {
// for complete code, see end of mail
}
// activating the handler here
document.onkeydown = DisableBackspace;
</script>
</head>

<body> <!-- i don't specify any handler in the body section
</body>

Scenario 2

<head>
<script language="javascript" type="text/javascript">
function DisableBackspace(e) {
// for complete code, see end of mail
}
// NOT activating the handler here
// document.onkeydown = DisableBackspace;
</script>
</head>

<body onkeydown="DisableBackspace(event);"> <!-- Activating here

onkeydown="return DisableBackspace(event);"

instead -->
</body>

but the 2nd scenario doesn't work.
why not?

thank you
Chris

Complete code:

<html>
<head>
<title></title>

<script language="javascript" type="text/javascript">
function DisableBackspace(e) {
if (!e)
e = window.event;

Remember to declare keycode as local:
var keycode;

if (e.keyCode)
keycode = e.keyCode; // IE
else
keycode = e.which; // Firefox

if (e.keyCode == 8)

Probably meant to check the keycode variable:
if (keycode == 8)

return false;
}
document.onkeydown = DisableBackspace; // uncomment
for Scenario 1
</script>

</head>
 <!-- uncomment

Return the result here too.

for Scenario 2: -->

<body>

</body>
</html>

Alternatively you can use the two other ways of cancelling the event
(IE and W3C DOM methods):

e.returnValue = false; // IE DOM
if (e.preventDefault) { e.preventDefault(); } // W3C DOM

Together they should stop the event just as efficiently as having
the handler return false in modern browsers and in IE.

/L

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event handler in <body> doesn't work

Chris

Martin Honnen

Lasse Reichstein Nielsen

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