1 // storage.js is loaded in the `<head>` of all rustdoc pages and doesn't
2 // use `async` or `defer`. That means it blocks further parsing and rendering
3 // of the page: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/script.
4 // This makes it the correct place to act on settings that affect the display of
5 // the page, so we don't see major layout changes during the load of the page.
8 const darkThemes = ["dark", "ayu"];
9 window.currentTheme = document.getElementById("themeStyle");
10 window.mainTheme = document.getElementById("mainThemeStyle");
12 // WARNING: RUSTDOC_MOBILE_BREAKPOINT MEDIA QUERY
13 // If you update this line, then you also need to update the media query with the same
14 // warning in rustdoc.css
15 window.RUSTDOC_MOBILE_BREAKPOINT = 700;
17 const settingsDataset = (function() {
18 const settingsElement = document.getElementById("default-settings");
19 if (settingsElement === null) {
22 const dataset = settingsElement.dataset;
23 if (dataset === undefined) {
29 function getSettingValue(settingName) {
30 const current = getCurrentValue(settingName);
31 if (current !== null) {
34 if (settingsDataset !== null) {
35 // See the comment for `default_settings.into_iter()` etc. in
36 // `Options::from_matches` in `librustdoc/config.rs`.
37 const def = settingsDataset[settingName.replace(/-/g,"_")];
38 if (def !== undefined) {
45 const localStoredTheme = getSettingValue("theme");
49 // eslint-disable-next-line no-unused-vars
50 function hasClass(elem, className) {
51 return elem && elem.classList && elem.classList.contains(className);
54 function addClass(elem, className) {
55 if (!elem || !elem.classList) {
58 elem.classList.add(className);
61 // eslint-disable-next-line no-unused-vars
62 function removeClass(elem, className) {
63 if (!elem || !elem.classList) {
66 elem.classList.remove(className);
70 * Run a callback for every element of an Array.
71 * @param {Array<?>} arr - The array to iterate over
72 * @param {function(?)} func - The callback
73 * @param {boolean} [reversed] - Whether to iterate in reverse
75 function onEach(arr, func, reversed) {
76 if (arr && arr.length > 0 && func) {
78 const length = arr.length;
79 for (let i = length - 1; i >= 0; --i) {
85 for (const elem of arr) {
96 * Turn an HTMLCollection or a NodeList into an Array, then run a callback
97 * for every element. This is useful because iterating over an HTMLCollection
98 * or a "live" NodeList while modifying it can be very slow.
99 * https://developer.mozilla.org/en-US/docs/Web/API/HTMLCollection
100 * https://developer.mozilla.org/en-US/docs/Web/API/NodeList
101 * @param {NodeList<?>|HTMLCollection<?>} lazyArray - An array to iterate over
102 * @param {function(?)} func - The callback
103 * @param {boolean} [reversed] - Whether to iterate in reverse
105 function onEachLazy(lazyArray, func, reversed) {
107 Array.prototype.slice.call(lazyArray),
112 function updateLocalStorage(name, value) {
114 window.localStorage.setItem("rustdoc-" + name, value);
116 // localStorage is not accessible, do nothing
120 function getCurrentValue(name) {
122 return window.localStorage.getItem("rustdoc-" + name);
128 function switchTheme(styleElem, mainStyleElem, newThemeName, saveTheme) {
129 // If this new value comes from a system setting or from the previously
130 // saved theme, no need to save it.
132 updateLocalStorage("theme", newThemeName);
135 if (savedHref.length === 0) {
136 onEachLazy(document.getElementsByTagName("link"), el => {
137 savedHref.push(el.href);
140 const newHref = savedHref.find(url => {
141 const m = url.match(/static\.files\/(.*)-[a-f0-9]{16}\.css$/);
142 if (m && m[1] === newThemeName) {
145 const m2 = url.match(/\/([^/]*)\.css$/);
146 if (m2 && m2[1].startsWith(newThemeName)) {
150 if (newHref && newHref !== styleElem.href) {
151 styleElem.href = newHref;
155 const updateTheme = (function() {
157 * Update the current theme to match whatever the current combination of
158 * * the preference for using the system theme
159 * (if this is the case, the value of preferred-light-theme, if the
160 * system theme is light, otherwise if dark, the value of
161 * preferred-dark-theme.)
162 * * the preferred theme
163 * … dictates that it should be.
165 function updateTheme() {
166 const use = (theme, saveTheme) => {
167 switchTheme(window.currentTheme, window.mainTheme, theme, saveTheme);
170 // maybe the user has disabled the setting in the meantime!
171 if (getSettingValue("use-system-theme") !== "false") {
172 const lightTheme = getSettingValue("preferred-light-theme") || "light";
173 const darkTheme = getSettingValue("preferred-dark-theme") || "dark";
176 use(darkTheme, true);
178 // prefers a light theme, or has no preference
179 use(lightTheme, true);
181 // note: we save the theme so that it doesn't suddenly change when
182 // the user disables "use-system-theme" and reloads the page or
183 // navigates to another page
185 use(getSettingValue("theme"), false);
189 // This is always updated below to a function () => bool.
192 // Determine the function for isDarkMode, and if we have
193 // `window.matchMedia`, set up an event listener on the preferred color
196 // Otherwise, fall back to the prefers-color-scheme value CSS captured in
197 // the "content" property.
198 if (window.matchMedia) {
199 // only listen to (prefers-color-scheme: dark) because light is the default
200 const mql = window.matchMedia("(prefers-color-scheme: dark)");
202 isDarkMode = () => mql.matches;
204 if (mql.addEventListener) {
205 mql.addEventListener("change", updateTheme);
207 // This is deprecated, see:
208 // https://developer.mozilla.org/en-US/docs/Web/API/MediaQueryList/addListener
209 mql.addListener(updateTheme);
212 // fallback to the CSS computed value
213 const cssContent = getComputedStyle(document.documentElement)
214 .getPropertyValue("content");
215 // (Note: the double-quotes come from that this is a CSS value, which
216 // might be a length, string, etc.)
217 const cssColorScheme = cssContent || "\"light\"";
218 isDarkMode = () => (cssColorScheme === "\"dark\"");
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);
236 if (getSettingValue("source-sidebar-show") === "true") {
237 // At this point in page load, `document.body` is not available yet.
238 // Set a class on the `<html>` element instead.
239 addClass(document.documentElement, "source-sidebar-expanded");
242 // If we navigate away (for example to a settings page), and then use the back or
243 // forward button to get back to a page, the theme may have changed in the meantime.
244 // But scripts may not be re-loaded in such a case due to the bfcache
245 // (https://web.dev/bfcache/). The "pageshow" event triggers on such navigations.
246 // Use that opportunity to update the theme.
247 // We use a setTimeout with a 0 timeout here to put the change on the event queue.
248 // For some reason, if we try to change the theme while the `pageshow` event is
249 // running, it sometimes fails to take effect. The problem manifests on Chrome,
250 // specifically when talking to a remote website with no caching.
251 window.addEventListener("pageshow", ev => {
253 setTimeout(updateTheme, 0);