jquery.input_formatter.js

(function($){
        $.fn.extend({
                formatInput: function(settings) {
                        var $elem = $(this);
                        settings = $.extend({
                                errback: null
                        }, settings);
                        $elem.bind("keyup.filter_input", $.fn.formatEvent);
                },
                formatEvent: function(e) {
                        //split with the "." because of the decimal value
                        var valueDecimal = initial_value.split(".");
                        //formats the part without the decimal part
                        var formatedValue = $.fn.insertSpaces(valueDecimal[0]);
                        var finalValue;
                        //checks if it has decimal values or not
                        if (valueDecimal.length > 1) {
                                finalValue = formatedValue + "." + valueDecimal[1];
                        } else {
                                finalValue = formatedValue;
                         }
                        elem.val(finalValue);
                        //I had to add this line because I'm working with knockout, and it wouldn't update the value on IE
                        elem.trigger('change');
                },
                insertSpaces: function(number) {
                        return number.replace(" ", "").replace(/(\d)(?=(?:\d{3})+$)/g, "$1 ");
                }
                });
})(jQuery);