Sv443
/
UserUtils-Mirror
-ын хуулбар https://github.com/Sv443-Network/UserUtils.git


			
				
					
						
						
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							/**
 * Returns `unsafeWindow` if the `@grant unsafeWindow` is given, otherwise falls back to the regular `window`
 */
export function getUnsafeWindow() {
  try {
    // throws ReferenceError if the "@grant unsafeWindow" isn't present
    return unsafeWindow;
  }
  catch(e) {
    return window;
  }
}

/**
 * Inserts {@linkcode afterElement} as a sibling just after the provided {@linkcode beforeElement}
 * @returns Returns the {@linkcode afterElement}
 */
export function insertAfter(beforeElement: Element, afterElement: Element) {
  beforeElement.parentNode?.insertBefore(afterElement, beforeElement.nextSibling);
  return afterElement;
}

/**
 * Adds a parent container around the provided element
 * @returns Returns the new parent element
 */
export function addParent(element: Element, newParent: Element) {
  const oldParent = element.parentNode;

  if(!oldParent)
    throw new Error("Element doesn't have a parent node");

  oldParent.replaceChild(newParent, element);
  newParent.appendChild(element);

  return newParent;
}

/**
 * Adds global CSS style in the form of a `<style>` element in the document's `<head>`  
 * This needs to be run after the `DOMContentLoaded` event has fired on the document object (or instantly if `@run-at document-end` is used).
 * @param style CSS string
 * @returns Returns the created style element
 */
export function addGlobalStyle(style: string) {
  const styleElem = document.createElement("style");
  styleElem.innerHTML = style;
  document.head.appendChild(styleElem);
  return styleElem;
}

/**
 * Preloads an array of image URLs so they can be loaded instantly from the browser cache later on
 * @param rejects If set to `true`, the returned PromiseSettledResults will contain rejections for any of the images that failed to load
 * @returns Returns an array of `PromiseSettledResult` - each resolved result will contain the loaded image element, while each rejected result will contain an `ErrorEvent`
 */
export function preloadImages(srcUrls: string[], rejects = false) {
  const promises = srcUrls.map(src => new Promise((res, rej) => {
    const image = new Image();
    image.src = src;
    image.addEventListener("load", () => res(image));
    image.addEventListener("error", (evt) => rejects && rej(evt));
  }));

  return Promise.allSettled(promises);
}

/**
 * Creates an invisible anchor with a `_blank` target and clicks it.  
 * Contrary to `window.open()`, this has a lesser chance to get blocked by the browser's popup blocker and doesn't open the URL as a new window.  
 *   
 * This function has to be run in response to a user interaction event, else the browser might reject it.
 */
export function openInNewTab(href: string) {
  const openElem = document.createElement("a");
  Object.assign(openElem, {
    className: "userutils-open-in-new-tab",
    target: "_blank",
    rel: "noopener noreferrer",
    href,
  });
  openElem.style.display = "none";

  document.body.appendChild(openElem);
  openElem.click();
  // timeout just to be safe
  setTimeout(openElem.remove, 50);
}

/**
 * Intercepts the specified event on the passed object and prevents it from being called if the called {@linkcode predicate} function returns a truthy value.  
 * If no predicate is specified, all events will be discarded.  
 * 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.  
 * Calling this function will set the `Error.stackTraceLimit` to 1000 to ensure the stack trace is preserved.
 */
export function interceptEvent<TEvtObj extends EventTarget, TPredicateEvt extends Event>(
  eventObject: TEvtObj,
  eventName: Parameters<TEvtObj["addEventListener"]>[0],
  predicate: (event: TPredicateEvt) => boolean = () => true,
) {
  // default is between 10 and 100 on conventional browsers so this should hopefully be more than enough
  // @ts-ignore
  if(typeof Error.stackTraceLimit === "number" && Error.stackTraceLimit < 1000) {
    // @ts-ignore
    Error.stackTraceLimit = 1000;
  }

  (function(original: typeof eventObject.addEventListener) {
    // @ts-ignore
    eventObject.__proto__.addEventListener = function(...args: Parameters<typeof eventObject.addEventListener>) {
      const origListener = typeof args[1] === "function" ? args[1] : args[1]?.handleEvent ?? (() => void 0);
      args[1] = function(...a) {
        if(args[0] === eventName && predicate((Array.isArray(a) ? a[0] : a) as TPredicateEvt))
          return;
        else
          return origListener.apply(this, a);
      };
      original.apply(this, args);
    };
    // @ts-ignore
  })(eventObject.__proto__.addEventListener);
}

/**
 * Intercepts the specified event on the window object and prevents it from being called if the called {@linkcode predicate} function returns a truthy value.  
 * If no predicate is specified, all events will be discarded.  
 * 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.  
 * Calling this function will set the `Error.stackTraceLimit` to 1000 to ensure the stack trace is preserved.
 */
export function interceptWindowEvent<TEvtKey extends keyof WindowEventMap>(
  eventName: TEvtKey,
  predicate: (event: WindowEventMap[TEvtKey]) => boolean = () => true,
) {  
  return interceptEvent(getUnsafeWindow(), eventName, predicate);
}

/** Checks if an element is scrollable in the horizontal and vertical directions */
export function isScrollable(element: Element) {
  const { overflowX, overflowY } = getComputedStyle(element);
  return {
    vertical: (overflowY === "scroll" || overflowY === "auto") && element.scrollHeight > element.clientHeight,
    horizontal: (overflowX === "scroll" || overflowX === "auto") && element.scrollWidth > element.clientWidth,
  };
}

/**
 * Executes the callback when the passed element's property changes.  
 * Contrary to an element's attributes, properties can usually not be observed with a MutationObserver.  
 * This function shims the getter and setter of the property to invoke the callback.  
 *   
 * [Source](https://stackoverflow.com/a/61975440)
 * @param property The name of the property to observe
 * @param callback Callback to execute when the value is changed
 */
export function observeElementProp<
  TElem extends Element = HTMLElement,
  TPropKey extends keyof TElem = keyof TElem,
>(
  element: TElem,
  property: TPropKey,
  callback: (oldVal: TElem[TPropKey], newVal: TElem[TPropKey]) => void
) {
  const elementPrototype = Object.getPrototypeOf(element);
  // eslint-disable-next-line no-prototype-builtins
  if(elementPrototype.hasOwnProperty(property)) {
    const descriptor = Object.getOwnPropertyDescriptor(elementPrototype, property);
    Object.defineProperty(element, property, {
      get: function() {
        // @ts-ignore
        // eslint-disable-next-line prefer-rest-params
        return descriptor?.get?.apply(this, arguments);
      },
      set: function() {
        const oldValue = this[property];
        // @ts-ignore
        // eslint-disable-next-line prefer-rest-params
        descriptor?.set?.apply(this, arguments);
        const newValue = this[property];
        if(typeof callback === "function") {
          // @ts-ignore
          callback.bind(this, oldValue, newValue);
        }
        return newValue;
      }
    });
  }
}