jQuery local link scroll animation

localScroll.js

$(document).on('click', 'a[href^="#"], a[data-scroll^="#"]', function(e) {
    var id = $(this).attr('href');

    if (/^#/.test(id)) {
        var $id = $(id);
        if ($id.length === 0) {
            return;
        }
    } else {
        id = "#" + id.split("#")[1];
    }

    e.preventDefault();

    var $_id = $(id),
        pos = $_id.offset().top;

    if (typeof $_id.attr('data-scroll-offset') !== "undefined") {
        pos = pos + ($_id.attr('data-scroll-offset') - 0);
    }

    $('body, html').animate({
        scrollTop: pos
    }, 800);
});