Allowing just Numeric Text on Input Text field

DEMO: http://so.devilmaycode.it/allowing-just-numeric-text-on-input-text-field/

jQuery.fn.onlyDigits = function() {
    var k;
    // little trick just in case you want use this:
    $('<span></span>').insertAfter(this);
    var $dText = $(this).next('span').hide();
    // Really cross-browser key event handler
    function Key(e) {
        if (!e.which && ((e.charCode ||
        e.charCode === 0) ? e.charCode: e.keyCode)) {
        e.which = e.charCode || e.keyCode;
        } return e.which; }
    return $(this).each(function() {
        $(this).keydown(function(e) {
            k = Key(e);
            return (
            // Allow CTRL+V , backspace, tab, delete, arrows,
            // numbers and keypad numbers ONLY
            ( k == 86 && e.ctrlKey ) || (k == 86 && e.metaKey) || k == 8 || k == 9 || k == 46 || (k >= 37 && k <= 40 && k !== 32 ) || (k >= 48 && k <= 57) || (k >= 96 && k <= 105));
        }).keyup(function(e) {
            var value = this.value.replace(/\s+/,'-');
            // Check if pasted content is Number
            if (isNaN(value)) {
                // re-add stored digits if CTRL+V have non digits chars
                $(this).val($dText.text());
            } else { // store digits only of easy access
                $dText.empty().append(value);
            }
        });
    });
};

USAGE:

$("#onlydigits").onlyDigits();

NOTE:

thanks to Insider for pointing out the past (cmd+v) for MAC

key event handler REFERENCES:

• http://unixpapa.com/js/key.html
• http://www.hallvord.com/opera/keyevents.htm
• http://dev.opera.com/articles/view/keyboard-accessible-web-applications-3/
• http://qooxdoo.org/documentation/0.7/keyboard_events
• http://msdn.microsoft.com/en-us/library/ms533927(VS.85).aspx
• http://www.quirksmode.org/js/keys.html
• http://www.w3.org/2002/09/tests/keys-cancel2.html

Thanks systempuntoout.. I've fixed this with following script

$('#input').keyup( function() {
  var $this = $(this);
  $this.val($this.val().replace(/[^\d.]/g, ''));     
});