Question

Is there a way to prevent the default action from occurring when the user presses backspace in a browser?

I don’t need to prevent the user from leaving, just from having the default backspace action. I need the backspace to do something different (it’s a game).

I tried without success:

window.addEventListener('keydown', function(e) {
    if (e.keyCode === Game.Key.BACK_SPACE)
    {
        e.preventDefault();
        e.stopPropagation();
        return false;
    }
}, false);

If I put an alert inside the if, the alert will be shown for backspace key press. So, the keyCode is correct.

This has to work in Opera 10.6, Firefox 4, Chrome 6, Internet Explorer 9 and Safari 5.

Answer 1

You don’t need return false or e.stopPropagation(); neither will make any difference in a listener attached with addEventListener. Your code won’t work in Opera, which only allows you to suppress the default browser behaviour in the keypress event, or IE <= 8, which doesn’t support addEventListener. The following should work in all browsers, so long as you don’t already have keydown and keypress event handlers on the document.

EDIT: It also now filters out events that originated from an <input> or <textarea> element:

function suppressBackspace(evt) {
    evt = evt || window.event;
    var target = evt.target || evt.srcElement;

    if (evt.keyCode == 8 && !/input|textarea/i.test(target.nodeName)) {
        return false;
    }
}

document.onkeydown = suppressBackspace;
document.onkeypress = suppressBackspace;