// Code for active links and scrolling

$(document).ready(function() {

$(".navbar-nav .nav-item .nav-link").on("click", function(){

$(".navbar-nav").find(".active").removeClass("active");

$(this).addClass("active");

});

// Automatic navigation active state.

var sections = $('section'),

nav = $('nav'),

nav_height = nav.outerHeight();

$(window).on('scroll', function () {

var cur_pos = $(this).scrollTop();

sections.each(function() {

var top = $(this).offset().top - nav_height - 85,

bottom = top + $(this).outerHeight();

if (cur_pos >= top && cur_pos <= bottom) {

if ($(window).width() >= 992 && this.id === "chapters") {

// pass - on large screens events & chapters are parallel,

// ignore chapters section then

} else {

nav.find('a').removeClass('active');

sections.removeClass('active');

$(this).addClass('active');

nav.find('a[href="#' + $(this).attr('id') + '"]').addClass('active');

}

}

});

});

// 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();

$('html, body').animate({

scrollTop: target.offset().top

}, 1000, 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

}

});

}

}

});

});