dom.ts 12 KB

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  1. /**
  2. * Returns `unsafeWindow` if the `@grant unsafeWindow` is given, otherwise falls back to the regular `window`
  3. */
  4. export function getUnsafeWindow(): Window {
  5. try {
  6. // throws ReferenceError if the "@grant unsafeWindow" isn't present
  7. return unsafeWindow;
  8. }
  9. catch(e) {
  10. return window;
  11. }
  12. }
  13. /**
  14. * Adds a parent container around the provided element
  15. * @returns Returns the new parent element
  16. */
  17. export function addParent<TElem extends Element, TParentElem extends Element>(element: TElem, newParent: TParentElem): TParentElem {
  18. const oldParent = element.parentNode;
  19. if(!oldParent)
  20. throw new Error("Element doesn't have a parent node");
  21. oldParent.replaceChild(newParent, element);
  22. newParent.appendChild(element);
  23. return newParent;
  24. }
  25. /**
  26. * Adds global CSS style in the form of a `<style>` element in the document's `<head>`
  27. * This needs to be run after the `DOMContentLoaded` event has fired on the document object (or instantly if `@run-at document-end` is used).
  28. * @param style CSS string
  29. * @returns Returns the created style element
  30. */
  31. export function addGlobalStyle(style: string): HTMLStyleElement {
  32. const styleElem = document.createElement("style");
  33. setInnerHtmlUnsafe(styleElem, style);
  34. document.head.appendChild(styleElem);
  35. return styleElem;
  36. }
  37. /**
  38. * Preloads an array of image URLs so they can be loaded instantly from the browser cache later on
  39. * @param rejects If set to `true`, the returned PromiseSettledResults will contain rejections for any of the images that failed to load
  40. * @returns Returns an array of `PromiseSettledResult` - each resolved result will contain the loaded image element, while each rejected result will contain an `ErrorEvent`
  41. */
  42. export function preloadImages(srcUrls: string[], rejects = false): Promise<PromiseSettledResult<HTMLImageElement>[]> {
  43. const promises = srcUrls.map(src => new Promise<HTMLImageElement>((res, rej) => {
  44. const image = new Image();
  45. image.src = src;
  46. image.addEventListener("load", () => res(image));
  47. image.addEventListener("error", (evt) => rejects && rej(evt));
  48. }));
  49. return Promise.allSettled(promises);
  50. }
  51. /**
  52. * Tries to use `GM.openInTab` to open the given URL in a new tab, otherwise if the grant is not given, creates an invisible anchor element and clicks it.
  53. * For the fallback to work, this function needs to be run in response to a user interaction event, else the browser might reject it.
  54. * @param href The URL to open in a new tab
  55. * @param background If set to `true`, the tab will be opened in the background - set to `undefined` (default) to use the browser's default behavior
  56. */
  57. export function openInNewTab(href: string, background?: boolean) {
  58. try {
  59. GM.openInTab(href, background);
  60. }
  61. catch(e) {
  62. const openElem = document.createElement("a");
  63. Object.assign(openElem, {
  64. className: "userutils-open-in-new-tab",
  65. target: "_blank",
  66. rel: "noopener noreferrer",
  67. href,
  68. });
  69. openElem.style.display = "none";
  70. document.body.appendChild(openElem);
  71. openElem.click();
  72. // timeout just to be safe
  73. setTimeout(openElem.remove, 50);
  74. }
  75. }
  76. /**
  77. * Intercepts the specified event on the passed object and prevents it from being called if the called {@linkcode predicate} function returns a truthy value.
  78. * If no predicate is specified, all events will be discarded.
  79. * This function should be called as soon as possible (I recommend using `@run-at document-start`), as it will only intercept events that are added after this function is called.
  80. * Calling this function will set `Error.stackTraceLimit = 100` (if not already higher) to ensure the stack trace is preserved.
  81. */
  82. export function interceptEvent<
  83. TEvtObj extends EventTarget,
  84. TPredicateEvt extends Event
  85. > (
  86. eventObject: TEvtObj,
  87. eventName: Parameters<TEvtObj["addEventListener"]>[0],
  88. predicate: (event: TPredicateEvt) => boolean = () => true,
  89. ): void {
  90. // @ts-ignore
  91. if((eventObject === window || eventObject === getUnsafeWindow()) && GM?.info?.scriptHandler && GM.info.scriptHandler === "FireMonkey")
  92. throw new Error("Intercepting window events is not supported on FireMonkey due to the isolated context the userscript runs in.");
  93. // default is 25 on FF so this should hopefully be more than enough
  94. // @ts-ignore
  95. Error.stackTraceLimit = Math.max(Error.stackTraceLimit, 100);
  96. if(isNaN(Error.stackTraceLimit))
  97. Error.stackTraceLimit = 100;
  98. (function(original: typeof eventObject.addEventListener) {
  99. // @ts-ignore
  100. eventObject.__proto__.addEventListener = function(...args: Parameters<typeof eventObject.addEventListener>) {
  101. const origListener = typeof args[1] === "function" ? args[1] : args[1]?.handleEvent ?? (() => void 0);
  102. args[1] = function(...a) {
  103. if(args[0] === eventName && predicate((Array.isArray(a) ? a[0] : a) as TPredicateEvt))
  104. return;
  105. else
  106. return origListener.apply(this, a);
  107. };
  108. original.apply(this, args);
  109. };
  110. // @ts-ignore
  111. })(eventObject.__proto__.addEventListener);
  112. }
  113. /**
  114. * Intercepts the specified event on the window object and prevents it from being called if the called {@linkcode predicate} function returns a truthy value.
  115. * If no predicate is specified, all events will be discarded.
  116. * This function should be called as soon as possible (I recommend using `@run-at document-start`), as it will only intercept events that are added after this function is called.
  117. * Calling this function will set `Error.stackTraceLimit = 100` (if not already higher) to ensure the stack trace is preserved.
  118. */
  119. export function interceptWindowEvent<TEvtKey extends keyof WindowEventMap>(
  120. eventName: TEvtKey,
  121. predicate: (event: WindowEventMap[TEvtKey]) => boolean = () => true,
  122. ): void {
  123. return interceptEvent(getUnsafeWindow(), eventName, predicate);
  124. }
  125. /** Checks if an element is scrollable in the horizontal and vertical directions */
  126. export function isScrollable(element: Element): Record<"vertical" | "horizontal", boolean> {
  127. const { overflowX, overflowY } = getComputedStyle(element);
  128. return {
  129. vertical: (overflowY === "scroll" || overflowY === "auto") && element.scrollHeight > element.clientHeight,
  130. horizontal: (overflowX === "scroll" || overflowX === "auto") && element.scrollWidth > element.clientWidth,
  131. };
  132. }
  133. /**
  134. * Executes the callback when the passed element's property changes.
  135. * Contrary to an element's attributes, properties can usually not be observed with a MutationObserver.
  136. * This function shims the getter and setter of the property to invoke the callback.
  137. *
  138. * [Source](https://stackoverflow.com/a/61975440)
  139. * @param property The name of the property to observe
  140. * @param callback Callback to execute when the value is changed
  141. */
  142. export function observeElementProp<
  143. TElem extends Element = HTMLElement,
  144. TPropKey extends keyof TElem = keyof TElem,
  145. > (
  146. element: TElem,
  147. property: TPropKey,
  148. callback: (oldVal: TElem[TPropKey], newVal: TElem[TPropKey]) => void
  149. ): void {
  150. const elementPrototype = Object.getPrototypeOf(element);
  151. // eslint-disable-next-line no-prototype-builtins
  152. if(elementPrototype.hasOwnProperty(property)) {
  153. const descriptor = Object.getOwnPropertyDescriptor(elementPrototype, property);
  154. Object.defineProperty(element, property, {
  155. get: function() {
  156. // @ts-ignore
  157. // eslint-disable-next-line prefer-rest-params
  158. return descriptor?.get?.apply(this, arguments);
  159. },
  160. set: function() {
  161. const oldValue = this[property];
  162. // @ts-ignore
  163. // eslint-disable-next-line prefer-rest-params
  164. descriptor?.set?.apply(this, arguments);
  165. const newValue = this[property];
  166. if(typeof callback === "function") {
  167. // @ts-ignore
  168. callback.bind(this, oldValue, newValue);
  169. }
  170. return newValue;
  171. }
  172. });
  173. }
  174. }
  175. /**
  176. * Returns a "frame" of the closest siblings of the {@linkcode refElement}, based on the passed amount of siblings and {@linkcode refElementAlignment}
  177. * @param refElement The reference element to return the relative closest siblings from
  178. * @param siblingAmount The amount of siblings to return
  179. * @param refElementAlignment Can be set to `center-top` (default), `center-bottom`, `top`, or `bottom`, which will determine where the relative location of the provided {@linkcode refElement} is in the returned array
  180. * @param includeRef If set to `true` (default), the provided {@linkcode refElement} will be included in the returned array at the corresponding position
  181. * @template TSibling The type of the sibling elements that are returned
  182. * @returns An array of sibling elements
  183. */
  184. export function getSiblingsFrame<
  185. TSibling extends Element = HTMLElement,
  186. > (
  187. refElement: Element,
  188. siblingAmount: number,
  189. refElementAlignment: "center-top" | "center-bottom" | "top" | "bottom" = "center-top",
  190. includeRef = true,
  191. ): TSibling[] {
  192. const siblings = [...refElement.parentNode?.childNodes ?? []] as TSibling[];
  193. const elemSiblIdx = siblings.indexOf(refElement as TSibling);
  194. if(elemSiblIdx === -1)
  195. throw new Error("Element doesn't have a parent node");
  196. if(refElementAlignment === "top")
  197. return [...siblings.slice(elemSiblIdx + Number(!includeRef), elemSiblIdx + siblingAmount + Number(!includeRef))];
  198. else if(refElementAlignment.startsWith("center-")) {
  199. // if the amount of siblings is even, one of the two center ones will be decided by the value of `refElementAlignment`
  200. const halfAmount = (refElementAlignment === "center-bottom" ? Math.ceil : Math.floor)(siblingAmount / 2);
  201. const startIdx = Math.max(0, elemSiblIdx - halfAmount);
  202. // if the amount of siblings is even, the top offset of 1 will be applied whenever `includeRef` is set to true
  203. const topOffset = Number(refElementAlignment === "center-top" && siblingAmount % 2 === 0 && includeRef);
  204. // if the amount of siblings is odd, the bottom offset of 1 will be applied whenever `includeRef` is set to true
  205. const btmOffset = Number(refElementAlignment === "center-bottom" && siblingAmount % 2 !== 0 && includeRef);
  206. const startIdxWithOffset = startIdx + topOffset + btmOffset;
  207. // filter out the reference element if `includeRef` is set to false,
  208. // then slice the array to the desired framing including the offsets
  209. return [
  210. ...siblings
  211. .filter((_, idx) => includeRef || idx !== elemSiblIdx)
  212. .slice(startIdxWithOffset, startIdxWithOffset + siblingAmount)
  213. ];
  214. }
  215. else if(refElementAlignment === "bottom")
  216. return [...siblings.slice(elemSiblIdx - siblingAmount + Number(includeRef), elemSiblIdx + Number(includeRef))];
  217. return [] as TSibling[];
  218. }
  219. let ttPolicy: { createHTML: (html: string) => string } | undefined;
  220. /**
  221. * Sets the innerHTML property of the provided element without any sanitation or validation.
  222. * Uses a [Trusted Types policy](https://developer.mozilla.org/en-US/docs/Web/API/Trusted_Types_API) on Chromium-based browsers to trick the browser into thinking the HTML is safe.
  223. * Use this if the page makes use of the CSP directive `require-trusted-types-for 'script'` and throws a "This document requires 'TrustedHTML' assignment" error on Chromium-based browsers.
  224. *
  225. * - ⚠️ This function does not perform any sanitization and should thus be used with utmost caution, as it can easily lead to XSS vulnerabilities!
  226. */
  227. export function setInnerHtmlUnsafe<TElement extends Element = HTMLElement>(element: TElement, html: string): TElement {
  228. // @ts-ignore
  229. if(!ttPolicy && typeof window?.trustedTypes?.createPolicy === "function") {
  230. // @ts-ignore
  231. ttPolicy = window.trustedTypes.createPolicy("_uu_set_innerhtml_unsafe", {
  232. createHTML: (unsafeHtml: string) => unsafeHtml,
  233. });
  234. }
  235. element.innerHTML = ttPolicy?.createHTML?.(html) ?? html;
  236. return element;
  237. }