Smoothly scroll to in-page fragment links

smoothscroll.jquery.js

// from https://css-tricks.com/snippets/jquery/smooth-scrolling/
// modified to use native scrollIntoView when supported

// Select all links with hashes
$('html').on('click', 'a[href*="#"]', 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();
            
            // Use native browser smooth scrolling when supported
            if ('scrollBehavior' in document.documentElement.style) {
                target[0].scrollIntoView({
                    behavior: 'smooth',
                    block: 'start',
                });
                
            // Use jquery smooth scrolling if animate is supported
            } else if ('animate' in $()) {
                $('html, body').animate({
                    scrollTop: target.offset().top
                }, 1000);
                
            // Use native browser jump when supported
            } else if ('scrollIntoView' in document.body) {
                target[0].scrollIntoView(true);
                
            // Use jquery jump worst case
            } else {
                $('html, body').scrollTop(target.offset().top);
            }
        }
    }
});