https://prakashsellathurai.com/static/js/theme.js

1(function () {
2    "use strict";
3
4    var STORAGE_KEY = "theme";
5    var DARK = "dark";
6    var LIGHT = "light";
7
8    function getPreferred() {
9        var stored = null;
10        try { stored = localStorage.getItem(STORAGE_KEY); } catch (e) { /* noop */ }
11        if (stored === DARK || stored === LIGHT) return stored;
12        if (window.matchMedia && window.matchMedia("(prefers-color-scheme: dark)").matches) {
13            return DARK;
14        }
15        return LIGHT;
16    }
17
18    function apply(theme) {
19        document.documentElement.setAttribute("data-theme", theme);
20        var btn = document.getElementById("theme-toggle");
21        if (btn) {
22            btn.setAttribute("aria-label", theme === DARK ? "Switch to light mode" : "Switch to dark mode");
23            btn.textContent = theme === DARK ? "\u2600\uFE0F" : "\uD83C\uDF19";
24        }
25    }
26
27    function toggle() {
28        var current = document.documentElement.getAttribute("data-theme") || LIGHT;
29        var next = current === DARK ? LIGHT : DARK;
30        apply(next);
31        try { localStorage.setItem(STORAGE_KEY, next); } catch (e) { /* noop */ }
32    }
33
34    /* Apply on load (the inline script in <head> already set data-theme,
35       but we update the button state here). */
36    apply(getPreferred());
37
38    function init() {
39        var btn = document.getElementById("theme-toggle");
40        if (btn) {
41            btn.addEventListener("click", toggle);
42            /* Re-apply so button label is correct */
43            apply(getPreferred());
44        }
45    }
46
47    if (document.readyState === "loading") {
48        document.addEventListener("DOMContentLoaded", init);
49    } else {
50        init();
51    }
52
53    /* Listen for OS theme changes */
54    if (window.matchMedia) {
55        window.matchMedia("(prefers-color-scheme: dark)").addEventListener("change", function (e) {
56            var stored = null;
57            try { stored = localStorage.getItem(STORAGE_KEY); } catch (ex) { /* noop */ }
58            if (!stored) {
59                apply(e.matches ? DARK : LIGHT);
60            }
61        });
62    }
63})();