Is there an opposite function of preventDefault() in JavaScript?

Wilkins picture Wilkins · Nov 6, 2009 · Viewed 32.2k times · Source

I am counting words in a text field and after a certain amount of words, I use prevent default. In the else, I would like to re-enable the default commands.

Does preventDefault() have an opposite function?

Here is some sample code:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>preventDefault</title>
    <style type="text/css"></style>
        <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
        <script type="text/javascript">
            $(function() {
                var wordNum = 3;
                var input_length;
                $("#max").text("max word(s): " + wordNum);
                $("#test").keypress(function(event) {

                    input_length = $.trim($(this).val())
                            .replace(/\s+/g, " ")
                            .split(' ').length;

                    if (input_length > (wordNum - 1)) {
                        event.preventDefault();
                    } else {
                        return true;
                    }
                });
            });

        </script>
        </head>
        <body>
            <div id="max"></div>
            <textarea id="test" cols="20" rows="5"></textarea>
</body>
</html>

It seems to work on IE, but Firefox doesn't like it.

Answer

Pickle picture Pickle · Nov 6, 2009

I think the problem you are having is that you are not looking for the delete key. Preventdefault does not cancel the event handler all together. But with your code once you hit the maximum length of your field the user will no longer be able delete any characters because the delete keypress is being cancelled.

The reason it works in IE is because IE does not fire the keypress event for delete, end, enter, escape, function keys, home, insert, pageUp/Down and tab. In Safari the keycode for delete is incorrect in the keypress event.

For these reasons I have a twofold suggestion; first, use the keydown event instead so that you get the correct keycodes.

Second, look at the keycode and if it is delete or backspace then don't preventDefault.

if ((event.keyCode != 46 && event.keyCode != 8) || input_length > (wordNum - 1)) {
    return false;
} else {
    return true;
}