// Thanks to Fluent UI for doing the [research on IE11 memory leak](https://github.com/microsoft/fluentui/pull/9010#issuecomment-490768427)
// and for creating this [utils](https://github.com/microsoft/fluentui/blob/f6af0479a54f17fd16b9616a62d6be38686a5c1e/packages/utilities/src/dom/getWindow.ts)

import { getDocument } from "./getDocument";

let _window: Window;

// Note: Accessing "window" in IE11 is somewhat expensive, and calling "typeof window"
// hits a memory leak, whereas aliasing it and calling "typeof _window" does not.
// Caching the window value at the file scope lets us minimize the impact.
try {
  _window = window;
} catch (e) {
  /* no-op */
}

/**
 * Returns `element.ownerDocument.defaultView || window`.
 */
export function getWindow(element?: Element): Window {
  if (!element) {
    return _window;
  }

  return getDocument(element).defaultView || _window;
}