bootstrap, make navbar stick to top when scrolling down

navbar-fixed-top.js

function setSkrollr(){
    var objDistance = $navbar.offset().top;
    $(window).scroll(function() {
        var myDistance = $(window).scrollTop();
        if (myDistance > objDistance){
            $navbar.addClass('navbar-fixed-top');
        }
        if (objDistance > myDistance){
            $navbar.removeClass('navbar-fixed-top');
        }
    });
}