dom.ts 11 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. // default is 25 on FF so this should hopefully be more than enough
  91. // @ts-ignore
  92. Error.stackTraceLimit = Math.max(Error.stackTraceLimit, 100);
  93. if(isNaN(Error.stackTraceLimit))
  94. Error.stackTraceLimit = 100;
  95. (function(original: typeof eventObject.addEventListener) {
  96. // @ts-ignore
  97. eventObject.__proto__.addEventListener = function(...args: Parameters<typeof eventObject.addEventListener>) {
  98. const origListener = typeof args[1] === "function" ? args[1] : args[1]?.handleEvent ?? (() => void 0);
  99. args[1] = function(...a) {
  100. if(args[0] === eventName && predicate((Array.isArray(a) ? a[0] : a) as TPredicateEvt))
  101. return;
  102. else
  103. return origListener.apply(this, a);
  104. };
  105. original.apply(this, args);
  106. };
  107. // @ts-ignore
  108. })(eventObject.__proto__.addEventListener);
  109. }
  110. /**
  111. * Intercepts the specified event on the window object and prevents it from being called if the called {@linkcode predicate} function returns a truthy value.
  112. * If no predicate is specified, all events will be discarded.
  113. * 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.
  114. * Calling this function will set `Error.stackTraceLimit = 100` (if not already higher) to ensure the stack trace is preserved.
  115. */
  116. export function interceptWindowEvent<TEvtKey extends keyof WindowEventMap>(
  117. eventName: TEvtKey,
  118. predicate: (event: WindowEventMap[TEvtKey]) => boolean = () => true,
  119. ): void {
  120. return interceptEvent(getUnsafeWindow(), eventName, predicate);
  121. }
  122. /** Checks if an element is scrollable in the horizontal and vertical directions */
  123. export function isScrollable(element: Element): Record<"vertical" | "horizontal", boolean> {
  124. const { overflowX, overflowY } = getComputedStyle(element);
  125. return {
  126. vertical: (overflowY === "scroll" || overflowY === "auto") && element.scrollHeight > element.clientHeight,
  127. horizontal: (overflowX === "scroll" || overflowX === "auto") && element.scrollWidth > element.clientWidth,
  128. };
  129. }
  130. /**
  131. * Executes the callback when the passed element's property changes.
  132. * Contrary to an element's attributes, properties can usually not be observed with a MutationObserver.
  133. * This function shims the getter and setter of the property to invoke the callback.
  134. *
  135. * [Source](https://stackoverflow.com/a/61975440)
  136. * @param property The name of the property to observe
  137. * @param callback Callback to execute when the value is changed
  138. */
  139. export function observeElementProp<
  140. TElem extends Element = HTMLElement,
  141. TPropKey extends keyof TElem = keyof TElem,
  142. > (
  143. element: TElem,
  144. property: TPropKey,
  145. callback: (oldVal: TElem[TPropKey], newVal: TElem[TPropKey]) => void
  146. ): void {
  147. const elementPrototype = Object.getPrototypeOf(element);
  148. // eslint-disable-next-line no-prototype-builtins
  149. if(elementPrototype.hasOwnProperty(property)) {
  150. const descriptor = Object.getOwnPropertyDescriptor(elementPrototype, property);
  151. Object.defineProperty(element, property, {
  152. get: function() {
  153. // @ts-ignore
  154. // eslint-disable-next-line prefer-rest-params
  155. return descriptor?.get?.apply(this, arguments);
  156. },
  157. set: function() {
  158. const oldValue = this[property];
  159. // @ts-ignore
  160. // eslint-disable-next-line prefer-rest-params
  161. descriptor?.set?.apply(this, arguments);
  162. const newValue = this[property];
  163. if(typeof callback === "function") {
  164. // @ts-ignore
  165. callback.bind(this, oldValue, newValue);
  166. }
  167. return newValue;
  168. }
  169. });
  170. }
  171. }
  172. /**
  173. * Returns a "frame" of the closest siblings of the {@linkcode refElement}, based on the passed amount of siblings and {@linkcode refElementAlignment}
  174. * @param refElement The reference element to return the relative closest siblings from
  175. * @param siblingAmount The amount of siblings to return
  176. * @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
  177. * @param includeRef If set to `true` (default), the provided {@linkcode refElement} will be included in the returned array at the corresponding position
  178. * @template TSibling The type of the sibling elements that are returned
  179. * @returns An array of sibling elements
  180. */
  181. export function getSiblingsFrame<
  182. TSibling extends Element = HTMLElement,
  183. > (
  184. refElement: Element,
  185. siblingAmount: number,
  186. refElementAlignment: "center-top" | "center-bottom" | "top" | "bottom" = "center-top",
  187. includeRef = true,
  188. ): TSibling[] {
  189. const siblings = [...refElement.parentNode?.childNodes ?? []] as TSibling[];
  190. const elemSiblIdx = siblings.indexOf(refElement as TSibling);
  191. if(elemSiblIdx === -1)
  192. throw new Error("Element doesn't have a parent node");
  193. if(refElementAlignment === "top")
  194. return [...siblings.slice(elemSiblIdx + Number(!includeRef), elemSiblIdx + siblingAmount + Number(!includeRef))];
  195. else if(refElementAlignment.startsWith("center-")) {
  196. // if the amount of siblings is even, one of the two center ones will be decided by the value of `refElementAlignment`
  197. const halfAmount = (refElementAlignment === "center-bottom" ? Math.ceil : Math.floor)(siblingAmount / 2);
  198. const startIdx = Math.max(0, elemSiblIdx - halfAmount);
  199. // if the amount of siblings is even, the top offset of 1 will be applied whenever `includeRef` is set to true
  200. const topOffset = Number(refElementAlignment === "center-top" && siblingAmount % 2 === 0 && includeRef);
  201. // if the amount of siblings is odd, the bottom offset of 1 will be applied whenever `includeRef` is set to true
  202. const btmOffset = Number(refElementAlignment === "center-bottom" && siblingAmount % 2 !== 0 && includeRef);
  203. const startIdxWithOffset = startIdx + topOffset + btmOffset;
  204. // filter out the reference element if `includeRef` is set to false,
  205. // then slice the array to the desired framing including the offsets
  206. return [
  207. ...siblings
  208. .filter((_, idx) => includeRef || idx !== elemSiblIdx)
  209. .slice(startIdxWithOffset, startIdxWithOffset + siblingAmount)
  210. ];
  211. }
  212. else if(refElementAlignment === "bottom")
  213. return [...siblings.slice(elemSiblIdx - siblingAmount + Number(includeRef), elemSiblIdx + Number(includeRef))];
  214. return [] as TSibling[];
  215. }
  216. let ttPolicy: { createHTML: (html: string) => string } | undefined;
  217. /**
  218. * Sets the innerHTML property of the provided element without any sanitation or validation.
  219. * 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.
  220. * 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.
  221. *
  222. * ⚠️ This function does not perform any sanitization and should thus be used with utmost caution, as it can easily lead to XSS vulnerabilities!
  223. */
  224. export function setInnerHtmlUnsafe<TElement extends Element = HTMLElement>(element: TElement, html: string): TElement {
  225. // @ts-ignore
  226. if(!ttPolicy && typeof window?.trustedTypes?.createPolicy === "function") {
  227. // @ts-ignore
  228. ttPolicy = window.trustedTypes.createPolicy("_uu_set_innerhtml_unsafe", {
  229. createHTML: (unsafeHtml: string) => unsafeHtml,
  230. });
  231. }
  232. element.innerHTML = ttPolicy?.createHTML?.(html) ?? html;
  233. return element;
  234. }