3 const darkThemes = ["dark", "ayu"];
4 window.currentTheme = document.getElementById("themeStyle");
5 window.mainTheme = document.getElementById("mainThemeStyle");
7 const settingsDataset = (function () {
8 const settingsElement = document.getElementById("default-settings");
9 if (settingsElement === null) {
12 const dataset = settingsElement.dataset;
13 if (dataset === undefined) {
19 function getSettingValue(settingName) {
20 const current = getCurrentValue(settingName);
21 if (current !== null) {
24 if (settingsDataset !== null) {
25 // See the comment for `default_settings.into_iter()` etc. in
26 // `Options::from_matches` in `librustdoc/config.rs`.
27 const def = settingsDataset[settingName.replace(/-/g,"_")];
28 if (def !== undefined) {
35 const localStoredTheme = getSettingValue("theme");
39 // eslint-disable-next-line no-unused-vars
40 function hasClass(elem, className) {
41 return elem && elem.classList && elem.classList.contains(className);
44 // eslint-disable-next-line no-unused-vars
45 function addClass(elem, className) {
46 if (!elem || !elem.classList) {
49 elem.classList.add(className);
52 // eslint-disable-next-line no-unused-vars
53 function removeClass(elem, className) {
54 if (!elem || !elem.classList) {
57 elem.classList.remove(className);
61 * Run a callback for every element of an Array.
62 * @param {Array<?>} arr - The array to iterate over
63 * @param {function(?)} func - The callback
64 * @param {boolean} [reversed] - Whether to iterate in reverse
66 function onEach(arr, func, reversed) {
67 if (arr && arr.length > 0 && func) {
69 const length = arr.length;
70 for (let i = length - 1; i >= 0; --i) {
76 for (const elem of arr) {
87 * Turn an HTMLCollection or a NodeList into an Array, then run a callback
88 * for every element. This is useful because iterating over an HTMLCollection
89 * or a "live" NodeList while modifying it can be very slow.
90 * https://developer.mozilla.org/en-US/docs/Web/API/HTMLCollection
91 * https://developer.mozilla.org/en-US/docs/Web/API/NodeList
92 * @param {NodeList<?>|HTMLCollection<?>} lazyArray - An array to iterate over
93 * @param {function(?)} func - The callback
94 * @param {boolean} [reversed] - Whether to iterate in reverse
96 function onEachLazy(lazyArray, func, reversed) {
98 Array.prototype.slice.call(lazyArray),
103 function updateLocalStorage(name, value) {
105 window.localStorage.setItem("rustdoc-" + name, value);
107 // localStorage is not accessible, do nothing
111 function getCurrentValue(name) {
113 return window.localStorage.getItem("rustdoc-" + name);
119 function switchTheme(styleElem, mainStyleElem, newTheme, saveTheme) {
120 const newHref = mainStyleElem.href.replace(
121 /\/rustdoc([^/]*)\.css/, "/" + newTheme + "$1" + ".css");
123 // If this new value comes from a system setting or from the previously
124 // saved theme, no need to save it.
126 updateLocalStorage("theme", newTheme);
129 if (styleElem.href === newHref) {
134 if (savedHref.length === 0) {
135 onEachLazy(document.getElementsByTagName("link"), el => {
136 savedHref.push(el.href);
139 onEach(savedHref, el => {
140 if (el === newHref) {
146 styleElem.href = newHref;
150 // This function is called from "main.js".
151 // eslint-disable-next-line no-unused-vars
152 function useSystemTheme(value) {
153 if (value === undefined) {
157 updateLocalStorage("use-system-theme", value);
159 // update the toggle if we're on the settings page
160 const toggle = document.getElementById("use-system-theme");
161 if (toggle && toggle instanceof HTMLInputElement) {
162 toggle.checked = value;
166 const updateSystemTheme = (function () {
167 if (!window.matchMedia) {
168 // fallback to the CSS computed value
170 const cssTheme = getComputedStyle(document.documentElement)
171 .getPropertyValue("content");
176 JSON.parse(cssTheme) || "light",
182 // only listen to (prefers-color-scheme: dark) because light is the default
183 const mql = window.matchMedia("(prefers-color-scheme: dark)");
185 function handlePreferenceChange(mql) {
186 const use = theme => {
187 switchTheme(window.currentTheme, window.mainTheme, theme, true);
189 // maybe the user has disabled the setting in the meantime!
190 if (getSettingValue("use-system-theme") !== "false") {
191 const lightTheme = getSettingValue("preferred-light-theme") || "light";
192 const darkTheme = getSettingValue("preferred-dark-theme") || "dark";
197 // prefers a light theme, or has no preference
200 // note: we save the theme so that it doesn't suddenly change when
201 // the user disables "use-system-theme" and reloads the page or
202 // navigates to another page
204 use(getSettingValue("theme"));
208 mql.addListener(handlePreferenceChange);
211 handlePreferenceChange(mql);
215 function switchToSavedTheme() {
219 getSettingValue("theme") || "light",
224 if (getSettingValue("use-system-theme") !== "false" && window.matchMedia) {
225 // update the preferred dark theme if the user is already using a dark theme
226 // See https://github.com/rust-lang/rust/pull/77809#issuecomment-707875732
227 if (getSettingValue("use-system-theme") === null
228 && getSettingValue("preferred-dark-theme") === null
229 && darkThemes.indexOf(localStoredTheme) >= 0) {
230 updateLocalStorage("preferred-dark-theme", localStoredTheme);
233 // call the function to initialize the theme at least once!
236 switchToSavedTheme();
239 // If we navigate away (for example to a settings page), and then use the back or
240 // forward button to get back to a page, the theme may have changed in the meantime.
241 // But scripts may not be re-loaded in such a case due to the bfcache
242 // (https://web.dev/bfcache/). The "pageshow" event triggers on such navigations.
243 // Use that opportunity to update the theme.
244 // We use a setTimeout with a 0 timeout here to put the change on the event queue.
245 // For some reason, if we try to change the theme while the `pageshow` event is
246 // running, it sometimes fails to take effect. The problem manifests on Chrome,
247 // specifically when talking to a remote website with no caching.
248 window.addEventListener("pageshow", ev => {
250 setTimeout(switchToSavedTheme, 0);