CODEWITHSUNDEEP
javascript
hova
hova

Reputation: 2841

How can I prevent Backspace from navigating back in javascript?

This works in IE, but I cannot get it to work in Opera or Firefox. I want to prevent Backspace from navigating away if and only if the current focus is the SELECT dropdown.

<html>
<body>
<select id="testselect">
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>
    <option value="4">4</option>
</select>
<script language="javascript">
    document.getElementById("testselect").onkeydown = function(e) {
        if(!e) {
            e = event;
        }
        alert(e.keyCode);
        if (e.keyCode == 8 || e.keyCode == 46) {
       e.returnValue = false;

        e.cancelBubble = true;
        if (e.stopPropagation) { e.stopPropagation(); alert("stoppropagation");}
        if (e.preventDefault) { e.preventDefault(); alert("preventdefault");}
        return false;
        }
    };
</script>
</body>
</html>

Upvotes: 13

Views: 8710

Answers (4)

CodeNepal
CodeNepal

Reputation: 902

Using jquery - for only select dropdown

$(document).ready(function(){ 
     //for IE use keydown, for Mozilla keypress  
     //as described in scr: http://www.codeproject.com/KB/scripting/PreventDropdownBackSpace.aspx
     $('select').keypress(function(event){if (event.keyCode == 8) {return false;}});
     $('select').keydown(function(event){if (event.keyCode == 8) {return false;}});
}

For all elements in page except input controls and textarea is as follows

<script type="text/javascript">

    //set this variable according to the need within the page
    var BACKSPACE_NAV_DISABLED = true;

    function fnPreventBackspace(event){if (BACKSPACE_NAV_DISABLED && event.keyCode == 8) {return false;}}
    function fnPreventBackspacePropagation(event){if(BACKSPACE_NAV_DISABLED && event.keyCode == 8){event.stopPropagation();}return true;}

    $(document).ready(function(){ 
        if(BACKSPACE_NAV_DISABLED){
            //for IE use keydown, for Mozilla keypress  
            //as described in scr: http://www.codeproject.com/KB/scripting/PreventDropdownBackSpace.aspx
            $(document).keypress(fnPreventBackspace);
            $(document).keydown(fnPreventBackspace);

            //Allow Backspace is the following controls
            $('input').keypress(fnPreventBackspacePropagation);
            $('input').keydown(fnPreventBackspacePropagation);
            $('textarea').keypress(fnPreventBackspacePropagation);
            $('textarea').keydown(fnPreventBackspacePropagation);
        }
    }); 

</script>

Upvotes: 9

hova
hova

Reputation: 2841

Well, turns out that Opera needs the event to be cancelled in the onkeypress event, not onkeydown.

Reference: http://jimblackler.net/blog/?p=20

Upvotes: 1

fordareh
fordareh

Reputation: 2963

That's trickier than I would have thought. Depending on the reason you are preventing the user from backspacing away from the page, something like this might work for you:

<script type="text/javascript">

        var bShowWarning = false;

        document.getElementById("testselect").onkeydown = function(e) {
            if (!e) {
                e = event;
            }
            if (e.keyCode == 8 || e.keyCode == 46) {
                bShowWarning = true;
            }
        };

        function UnLoadWindow() {
            if (!bShowWarning) return;
            return 'If you leave the page your data will be lost.';
        }

        window.onbeforeunload = UnLoadWindow;
    </script>

Upvotes: 2

Robert Harvey
Robert Harvey

Reputation: 180798

You might want to check out the source code for the project from this article. He goes into detail about how he had to contend with the backspace key in different browsers.

Upvotes: 0

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