book.js

"use strict";

// Fix back button cache problem
window.onunload = function () { };

(function sidebar() {
    var html = document.querySelector("html");
    var sidebar = document.getElementById("sidebar");
    var sidebarLinks = document.querySelectorAll('#sidebar a');
    var sidebarToggleButton = document.getElementById("sidebar-toggle");
    var firstContact = null;

    function showSidebar() {
        html.classList.remove('sidebar-hidden')
        html.classList.add('sidebar-visible');
        Array.from(sidebarLinks).forEach(function (link) {
            link.setAttribute('tabIndex', 0);
        });
        sidebarToggleButton.setAttribute('aria-expanded', true);
        sidebar.setAttribute('aria-hidden', false);
        try { localStorage.setItem('mdbook-sidebar', 'visible'); } catch (e) { }
    }

    function hideSidebar() {
        html.classList.remove('sidebar-visible')
        html.classList.add('sidebar-hidden');
        Array.from(sidebarLinks).forEach(function (link) {
            link.setAttribute('tabIndex', -1);
        });
        sidebarToggleButton.setAttribute('aria-expanded', false);
        sidebar.setAttribute('aria-hidden', true);
        try { localStorage.setItem('mdbook-sidebar', 'hidden'); } catch (e) { }
    }

    // Toggle sidebar
    sidebarToggleButton.addEventListener('click', function sidebarToggle() {
        if (html.classList.contains("sidebar-hidden")) {
            showSidebar();
        } else if (html.classList.contains("sidebar-visible")) {
            hideSidebar();
        } else {
            if (getComputedStyle(sidebar)['transform'] === 'none') {
                hideSidebar();
            } else {
                showSidebar();
            }
        }
    });

    document.addEventListener('touchstart', function (e) {
        firstContact = {
            x: e.touches[0].clientX,
            time: Date.now()
        };
    }, { passive: true });

    document.addEventListener('touchmove', function (e) {
        if (!firstContact)
            return;

        var curX = e.touches[0].clientX;
        var xDiff = curX - firstContact.x,
            tDiff = Date.now() - firstContact.time;

        if (tDiff < 250 && Math.abs(xDiff) >= 150) {
            if (xDiff >= 0 && firstContact.x < Math.min(document.body.clientWidth * 0.25, 300))
                showSidebar();
            else if (xDiff < 0 && curX < 300)
                hideSidebar();

            firstContact = null;
        }
    }, { passive: true });

    // Scroll sidebar to current active section
    var activeSection = sidebar.querySelector(".active");
    if (activeSection) {
        sidebar.scrollTop = activeSection.offsetTop;
    }
})();

(function chapterNavigation() {
    document.addEventListener('keydown', function (e) {
        if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) { return; }
        if (window.search && window.search.hasFocus()) { return; }

        switch (e.key) {
            case 'ArrowRight':
                e.preventDefault();
                var nextButton = document.querySelector('.nav-chapters.next');
                if (nextButton) {
                    window.location.href = nextButton.href;
                }
                break;
            case 'ArrowLeft':
                e.preventDefault();
                var previousButton = document.querySelector('.nav-chapters.previous');
                if (previousButton) {
                    window.location.href = previousButton.href;
                }
                break;
        }
    });
})();