Get Parent of DOM Object 1

maxhugen · Jun 10, 2008

I'm trying to capture and prevent the Backspace keypress from sending the Browser back, when a user is in a form, as some have lost the data they've entered after pressing backspace.

However, I need to allow it when I'm in a form field. The code I'm using so far is successfully preventing the Backspace, but in all circumstances:

Code:

function CancelBackspace(e) {
    var keyPressed = (e.which)?e.which:window.event.keyCode;
    return (keyPressed==8)?false:true;
}

<body onkeydown="return CancelBackspace(event)">

Is there some way that I could use target property of the event, and determine if the target's parent is a form?

MTIA

Max Hugen
Australia

tsuji · Jun 10, 2008

You can do it like this.
[tt]
function CancelBackspace(e) {
var keyPressed = (e.which)?e.which:window.event.keyCode;
var b_form=(e.target)?(!!e.target.form)

!!window.event.srcElement.form);
return (keyPressed==8 && !b_form)?false:true;
}[/tt]

maxhugen · Jun 11, 2008

Thanks tsuji

That works fine. Just a question pls: what is the actual meaning of "!!" ? (seems like "not not"...)

Thanks, Max

Max Hugen
Australia

tsuji · Jun 11, 2008

It just coerses the probing of existence of attributes or methods to boolean return leaving no alternative to the interpretation of the intension of the scripters. In some restricted situations, I like to make that semantic explicit to the comfort of scripters at the expense of cpu cycles. In some others, let the default behaviour of the script engine would suffice.

BillyRayPreachersSon · Jun 11, 2008

Max,

You could probably use "===" or "!==" to the same effect.

Dan

Coedit Limited - Delivering standards compliant, accessible web solutions

[tt]Dan's Page [blue]@[/blue] Code Couch

http://www.codecouch.com/dan/

[/tt]

maxhugen · Jun 11, 2008

Thanks tsuji, its very elegant... now that I've been thinking on it more, I can see that the first "!" forces a boolean result, and the second "!" reverses the boolean to the output we'd like. Cool.

Max Hugen
Australia

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Get Parent of DOM Object 1

maxhugen

Programmer

tsuji

Technical User

maxhugen

Programmer

tsuji

Technical User

BillyRayPreachersSon

Programmer

maxhugen

Programmer

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