TonyTheJet TonyTheJet - 1 month ago 9
Javascript Question

How can I disabling backspace key press on all browsers?

I'm trying to disable the backspace button on an order page in all cases except when a textarea or text input is an active element to prevent users from accidentally backing out of an order. I have it working fine in most browsers, but in IE (testing in IE9, both regular and compatibility mode) it still allows the user to hit the backspace and go to the previous page.

Here's the code:

$(document).keypress(function(e){
var activeNodeName=document.activeElement.nodeName;
var activeElType=document.activeElement.type;
if (e.keyCode==8 && activeNodeName != 'INPUT' && activeNodeName != 'TEXTAREA'){
return false;
} else {
if (e.keyCode==8 && activeNodeName=='INPUT' && activeElType != 'TEXT' && activeElType != 'text'){
return false;
}
}
});


Any advice on what I'm doing wrong here?

Thanks!

Answer

I think you're overcomplicating that. Rather than checking for an active element, find the event target instead. This should give you the information you need. It's also better to use keydown rather than keypress when there is no visible character. Finally, it's better to use e.preventDefault() for better granularity.

$(document).keydown(function(e) {
    var nodeName = e.target.nodeName.toLowerCase();

    if (e.which === 8) {
        if ((nodeName === 'input' && e.target.type === 'text') ||
            nodeName === 'textarea') {
            // do nothing
        } else {
            e.preventDefault();
        }
    }
});

NB I could have done this the other way round, rather than an empty if block and all the code going in the else block, but I think this is more readable.