Function getUntaintedPrototype

packages/utils/src/index.ts:57–131

(
  key: T,
)

};

export function getUntaintedPrototype<T extends keyof BasePrototypeCache>(
  key: T,
): BasePrototypeCache[T] {
  if (untaintedBasePrototype[key])
    return untaintedBasePrototype[key] as BasePrototypeCache[T];

  const defaultObj = globalThis[key] as TypeofPrototypeOwner;
  const defaultPrototype = defaultObj.prototype as BasePrototypeCache[T];

  // use list of testable accessors to check if the prototype is tainted
  const accessorNames =
    key in testableAccessors ? testableAccessors[key] : undefined;
  const isUntaintedAccessors = Boolean(
    accessorNames &&
      // @ts-expect-error 2345
      accessorNames.every((accessor: keyof typeof defaultPrototype) =>
        Boolean(
          Object.getOwnPropertyDescriptor(defaultPrototype, accessor)
            ?.get?.toString()
            .includes('[native code]'),
        ),
      ),
  );

  const methodNames = key in testableMethods ? testableMethods[key] : undefined;
  const isUntaintedMethods = Boolean(
    methodNames &&
      methodNames.every(
        // @ts-expect-error 2345
        (method: keyof typeof defaultPrototype) =>
          typeof defaultPrototype[method] === 'function' &&
          defaultPrototype[method]?.toString().includes('[native code]'),
      ),
  );

  if (isUntaintedAccessors && isUntaintedMethods && !isAngularZonePresent()) {
    untaintedBasePrototype[key] = defaultObj.prototype as BasePrototypeCache[T];
    return defaultObj.prototype as BasePrototypeCache[T];
  }

  try {
    const iframeEl = document.createElement('iframe');
    iframeEl.style.display = 'none';
    document.body.appendChild(iframeEl);
    const win = iframeEl.contentWindow;
    if (!win) return defaultObj.prototype as BasePrototypeCache[T];

    // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-explicit-any
    const untaintedObject = (win as any)[key]
      .prototype as BasePrototypeCache[T];

    if (!untaintedObject) {
      iframeEl.remove();
      return defaultPrototype;
    }

    // WebKit/Safari: WebKit tears down an iframe's ScriptExecutionContext when it is
    // detached from the DOM. MutationObserver.deliver() silently drops callbacks when