Input Mask

(function($) {
$.fn.mask = function() {
                return $(this).each(function() {
                        var
                                $this = $(this),
                                text = $this.val();
 
                        //when focused ont the input
                        $this.focus(function(){
                                if($this.val() == text)
                                        $this.val("");
                        });
                        //looses focus
                        $this.blur(function() {
                                if($this.val() == "")
                                        $this.val(text);
                        });
                });
        }
})(jQuery);
 
$(document).ready(function() {
       $('#input').mask();
});