how to implement the smooth scrolling code example

Example: smooth scroll

/* ==========================================================================
   Smooth scroll
   ========================================================================== */
$('a[href*=#]:not([href=#])').on('click', function() {
    if (location.pathname.replace(/^\//, '') === this.pathname.replace(/^\//, '') && location.hostname === this.hostname) {
        var target = $(this.hash);
        target = target.length ? target : $('[name=' + this.hash.slice(1) + ']');
        if (target.length) {
            $('html,body').animate({

                scrollTop: (target.offset().top - 40)
            }, 1000);
            return false;
        }
    }
});