src/librustdoc/html/static/js/storage.js

   1 "use strict";
   2
   3 const darkThemes = ["dark", "ayu"];
   4 window.currentTheme = document.getElementById("themeStyle");
   5 window.mainTheme = document.getElementById("mainThemeStyle");
   6
   7 const settingsDataset = (function () {
   8     const settingsElement = document.getElementById("default-settings");
   9     if (settingsElement === null) {
  10         return null;
  11     }
  12     const dataset = settingsElement.dataset;
  13     if (dataset === undefined) {
  14         return null;
  15     }
  16     return dataset;
  17 })();
  18
  19 function getSettingValue(settingName) {
  20     const current = getCurrentValue(settingName);
  21     if (current !== null) {
  22         return current;
  23     }
  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) {
  29             return def;
  30         }
  31     }
  32     return null;
  33 }
  34
  35 const localStoredTheme = getSettingValue("theme");
  36
  37 const savedHref = [];
  38
  39 // eslint-disable-next-line no-unused-vars
  40 function hasClass(elem, className) {
  41     return elem && elem.classList && elem.classList.contains(className);
  42 }
  43
  44 // eslint-disable-next-line no-unused-vars
  45 function addClass(elem, className) {
  46     if (!elem || !elem.classList) {
  47         return;
  48     }
  49     elem.classList.add(className);
  50 }
  51
  52 // eslint-disable-next-line no-unused-vars
  53 function removeClass(elem, className) {
  54     if (!elem || !elem.classList) {
  55         return;
  56     }
  57     elem.classList.remove(className);
  58 }
  59
  60 /**
  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
  65  */
  66 function onEach(arr, func, reversed) {
  67     if (arr && arr.length > 0 && func) {
  68         if (reversed) {
  69             const length = arr.length;
  70             for (let i = length - 1; i >= 0; --i) {
  71                 if (func(arr[i])) {
  72                     return true;
  73                 }
  74             }
  75         } else {
  76             for (const elem of arr) {
  77                 if (func(elem)) {
  78                     return true;
  79                 }
  80             }
  81         }
  82     }
  83     return false;
  84 }
  85
  86 /**
  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
  95  */
  96 function onEachLazy(lazyArray, func, reversed) {
  97     return onEach(
  98         Array.prototype.slice.call(lazyArray),
  99         func,
 100         reversed);
 101 }
 102
 103 // eslint-disable-next-line no-unused-vars
 104 function hasOwnPropertyRustdoc(obj, property) {
 105     return Object.prototype.hasOwnProperty.call(obj, property);
 106 }
 107
 108 function updateLocalStorage(name, value) {
 109     try {
 110         window.localStorage.setItem("rustdoc-" + name, value);
 111     } catch(e) {
 112         // localStorage is not accessible, do nothing
 113     }
 114 }
 115
 116 function getCurrentValue(name) {
 117     try {
 118         return window.localStorage.getItem("rustdoc-" + name);
 119     } catch(e) {
 120         return null;
 121     }
 122 }
 123
 124 function switchTheme(styleElem, mainStyleElem, newTheme, saveTheme) {
 125     const newHref = mainStyleElem.href.replace(
 126         /\/rustdoc([^/]*)\.css/, "/" + newTheme + "$1" + ".css");
 127
 128     // If this new value comes from a system setting or from the previously
 129     // saved theme, no need to save it.
 130     if (saveTheme) {
 131         updateLocalStorage("theme", newTheme);
 132     }
 133
 134     if (styleElem.href === newHref) {
 135         return;
 136     }
 137
 138     let found = false;
 139     if (savedHref.length === 0) {
 140         onEachLazy(document.getElementsByTagName("link"), el => {
 141             savedHref.push(el.href);
 142         });
 143     }
 144     onEach(savedHref, el => {
 145         if (el === newHref) {
 146             found = true;
 147             return true;
 148         }
 149     });
 150     if (found) {
 151         styleElem.href = newHref;
 152     }
 153 }
 154
 155 // This function is called from "main.js".
 156 // eslint-disable-next-line no-unused-vars
 157 function useSystemTheme(value) {
 158     if (value === undefined) {
 159         value = true;
 160     }
 161
 162     updateLocalStorage("use-system-theme", value);
 163
 164     // update the toggle if we're on the settings page
 165     const toggle = document.getElementById("use-system-theme");
 166     if (toggle && toggle instanceof HTMLInputElement) {
 167         toggle.checked = value;
 168     }
 169 }
 170
 171 const updateSystemTheme = (function () {
 172     if (!window.matchMedia) {
 173         // fallback to the CSS computed value
 174         return () => {
 175             const cssTheme = getComputedStyle(document.documentElement)
 176                 .getPropertyValue("content");
 177
 178             switchTheme(
 179                 window.currentTheme,
 180                 window.mainTheme,
 181                 JSON.parse(cssTheme) || "light",
 182                 true
 183             );
 184         };
 185     }
 186
 187     // only listen to (prefers-color-scheme: dark) because light is the default
 188     const mql = window.matchMedia("(prefers-color-scheme: dark)");
 189
 190     function handlePreferenceChange(mql) {
 191         const use = theme => {
 192             switchTheme(window.currentTheme, window.mainTheme, theme, true);
 193         };
 194         // maybe the user has disabled the setting in the meantime!
 195         if (getSettingValue("use-system-theme") !== "false") {
 196             const lightTheme = getSettingValue("preferred-light-theme") || "light";
 197             const darkTheme = getSettingValue("preferred-dark-theme") || "dark";
 198
 199             if (mql.matches) {
 200                 use(darkTheme);
 201             } else {
 202                 // prefers a light theme, or has no preference
 203                 use(lightTheme);
 204             }
 205             // note: we save the theme so that it doesn't suddenly change when
 206             // the user disables "use-system-theme" and reloads the page or
 207             // navigates to another page
 208         } else {
 209             use(getSettingValue("theme"));
 210         }
 211     }
 212
 213     mql.addListener(handlePreferenceChange);
 214
 215     return () => {
 216         handlePreferenceChange(mql);
 217     };
 218 })();
 219
 220 function switchToSavedTheme() {
 221     switchTheme(
 222         window.currentTheme,
 223         window.mainTheme,
 224         getSettingValue("theme") || "light",
 225         false
 226     );
 227 }
 228
 229 if (getSettingValue("use-system-theme") !== "false" && window.matchMedia) {
 230     // update the preferred dark theme if the user is already using a dark theme
 231     // See https://github.com/rust-lang/rust/pull/77809#issuecomment-707875732
 232     if (getSettingValue("use-system-theme") === null
 233         && getSettingValue("preferred-dark-theme") === null
 234         && darkThemes.indexOf(localStoredTheme) >= 0) {
 235         updateLocalStorage("preferred-dark-theme", localStoredTheme);
 236     }
 237
 238     // call the function to initialize the theme at least once!
 239     updateSystemTheme();
 240 } else {
 241     switchToSavedTheme();
 242 }
 243
 244 // If we navigate away (for example to a settings page), and then use the back or
 245 // forward button to get back to a page, the theme may have changed in the meantime.
 246 // But scripts may not be re-loaded in such a case due to the bfcache
 247 // (https://web.dev/bfcache/). The "pageshow" event triggers on such navigations.
 248 // Use that opportunity to update the theme.
 249 // We use a setTimeout with a 0 timeout here to put the change on the event queue.
 250 // For some reason, if we try to change the theme while the `pageshow` event is
 251 // running, it sometimes fails to take effect. The problem manifests on Chrome,
 252 // specifically when talking to a remote website with no caching.
 253 window.addEventListener("pageshow", ev => {
 254     if (ev.persisted) {
 255         setTimeout(switchToSavedTheme, 0);
 256     }
 257 });