custom.js

$(document).ready(function () {
// Select all links with hashes
    $('a[href*="#"]')
    // Remove links that don't actually link to anything
        .not('[href="#"]')
        .not('[href="#0"]')
        .click(function (event) {
            // On-page links
            if (
                location.pathname.replace(/^\//, '') === this.pathname.replace(/^\//, '')
                &&
                location.hostname === this.hostname
            ) {
                // Figure out element to scroll to

                var target = $(this.hash);

                target = target.length ? target : $('[name=' + this.hash.slice(1) + ']');
                // Does a scroll target exist?
                if (target.length) {
                    // Only prevent default if animation is actually gonna happen

                    event.preventDefault();
                    history.replaceState(null, null, document.location.pathname + this.hash);

                    $('html, body').animate({
                        scrollTop: target.offset().top
                    }, 600, function () {
                        // Callback after animation
                        // Must change focus!
                        var $target = $(target);
                        //$target.focus();
                        if ($target.is(':focus')) { // Checking if the target was focused
                            return false;
                        } else {
                            $target.attr('tabindex', '-1'); // Adding tabindex for elements not focusable
                            //$target.focus(); // Set focus again
                        }
                    });
                }
            }
        });
});