getWindowPosition.ts

const offsetBase = document.createElement('div');
offsetBase.style.cssText = 'position:absolute;left:0;top:0';
document.body.appendChild(offsetBase);

export default function getWindowPosition(node: Element) {
  const boundingRect = node.getBoundingClientRect();
  const baseRect = offsetBase.getBoundingClientRect();

  const left = boundingRect.left - baseRect.left;
  const top = boundingRect.top - baseRect.top;
  const width = boundingRect.right - boundingRect.left;
  const height = boundingRect.bottom - boundingRect.top;

  return {
    ...boundingRect,
    left,
    top,
    width,
    height,
    right: left + width,
    bottom: top + height,
  };
}