website-risg/templates/app.js

document.addEventListener("DOMContentLoaded", function () {
    changeTheme();
    initcolorTheme();
    apply_stickies();
});

function changeTheme() {
    let toggleBtn = document.querySelector("#theme-toggle-js");

    if (toggleBtn) {
        toggleBtn.addEventListener("click", function () {
            if (toggleBtn.dataset.theme === "light") {
                setTheme("dark", true);
            } else {
                setTheme("light", true);
            }
        });
    }
}

/***
 * init javascript
 * 1) detect native color scheme or use set theme in local storage
 * 2) detect view (desktop or responsive) if on mobile device with touch screen
 * 3) set base font size to 112.5% -> 18px
 */
function initcolorTheme() {
    colorThemeWatcher();
    let theme = localStorage.getItem("theme");
    if (theme == null || theme === "auto") {
        if (window.matchMedia && window.matchMedia("(prefers-color-scheme: dark)").matches) {
            setTheme("dark", false);
        } else {
            setTheme("light", false);
        }
    } else {
        setTheme(theme);
    }
}

/***
 * Listener operating system native color configuration
 */
function colorThemeWatcher() {
    try {
        window.matchMedia("(prefers-color-scheme: dark)").addEventListener("change", (e) => {
            setTheme(e.matches ? "dark" : "light");
        });
    } catch {
        console.warn("color theme watcher not supported");
    }
}

/**
 * Define color scheme, colors without losing the base font size configuration
 * and add data-theme to html tag
 * @param theme
 */
function setTheme(theme, setLocalStorage = true) {
    let toggleBtn = document.querySelector("#theme-toggle-js");

    if (setLocalStorage) {
        localStorage.setItem("theme", theme);
    }
    if (toggleBtn) toggleBtn.setAttribute("data-theme", theme);

    if (document.documentElement.dataset.theme === "dark" && theme === "light") {
        document.documentElement.dataset.theme = "light";
    } else if (document.documentElement.dataset.theme === "light" && theme === "dark") {
        document.documentElement.dataset.theme = "dark";
    }
}

window.addEventListener("scroll", function () {
    apply_stickies();
});

function apply_stickies() {
    var _$stickies = [].slice.call(document.querySelectorAll(".sticky"));
    _$stickies.forEach(function (_$sticky) {
        if (CSS.supports && CSS.supports("position", "sticky")) {
            apply_sticky_class(_$sticky);
        }
    });
}

function apply_sticky_class(_$sticky) {
    var currentOffset = _$sticky.getBoundingClientRect().top;
    var stickyOffset = parseInt(getComputedStyle(_$sticky).top.replace("px", ""));
    var isStuck = currentOffset <= stickyOffset;

    _$sticky.classList.toggle("js-is-sticky", isStuck);
}