Different scope approach

jquery.input_formatter.js

(function($){
        $.fn.extend({
                formatInput: function(custom_settings) {
                        var settings = $.extend({
                                regex:".*",
                                format_number: true,
                                max_length: false,
                                errback: undefined
                        }, custom_settings);
                        return this.each(function() {
                                var elem = $(this);
                                if(settings.format_number == true)
                                {
                                        elem.bind("keyup.format_number", formatEvent);
                                }
                                elem.bind("keypress.filter_input", filterEvent);
                        });

                        function filterEvent(e) {
                                var s = settings;
                                var regex = new RegExp(s.regex);
                                var key = e.charCode ? e.charCode : e.keyCode ? e.keyCode : 0;
                                var string = String.fromCharCode(key);
                                var elem = $(this);
                                if (key == 8 || key == 9 || key == 13 || key == 35 || key == 36|| key == 37 || key == 39 || key == 46) {

                                        if ($.browser.mozilla) {
                                                if (event.charCode == 0 && event.keyCode == key) {
                                                        return true;                                             
                                                }

                                        }
                                }
                                if(s.max_length != false)
                                {
                                        var value = elem.val();
                                        if(value != undefined && value.length >= s.max_length)
                                        {
                                                if(s.errback != undefined)
                                                {
                                                        s.errback(elem, reason="max_length");
                                                }
                                                return false;
                                        }
                                }
                                if(regex.test(string))
                                {
                                        return true;
                                } else {
                                        if(s.errback != undefined)
                                        {
                                                s.errback(elem, reason="regex");
                                        }
                                        return false;
                                }
                        };
                        function formatEvent(e) {
                                var elem = $(this);
                                var initial_value = elem.val().replace(" ", "");
                                elem.val(insertSpaces(initial_value));
                        };
                        function insertSpaces(number) {
                                return number.replace(/(\d)(?=(?:\d{3})+$)/g, "$1 ");
                        };
                },
                });
})(jQuery);