src/plugins/popper/index.js
function getFixedPositionOffsetParent(element) {
  // This check is needed to avoid errors in case one of the elements isn't defined for any reason
  if (!element || !element.parentElement || isIE()) {
    return document.documentElement;
  }
  var el = element.parentElement;
  while (el && getStyleComputedProperty(el, 'transform') === 'none') {
    el = el.parentElement;
  }
  return el || document.documentElement;
}
function getFixedPositionOffsetParent(element) {
  // This check is needed to avoid errors in case one of the elements isn't defined for any reason
  if (!element || !element.parentElement || isIE()) {
    return document.documentElement;
  }
  var el = element.parentElement;
  while (el && getStyleComputedProperty(el, 'transform') === 'none') {
    el = el.parentElement;
  }
  return el || document.documentElement;
}
function getFixedPositionOffsetParent ( element ) { // This check is needed to avoid errors in case one of the elements isn't defined for any reason if ( ! element || ! element . parentElement || isIE ( ) ) { return document . documentElement ; } var el = element . parentElement ; while ( el && getStyleComputedProperty ( el , 'transform' ) === 'none' ) { el = el . parentElement ; } return el || document . documentElement ; }
Finds the first parent of an element that has a transformed property defined
@method
@memberof Popper.Utils
@argument {Element} element
@returns {Element} first transformed parent or documentElement
Finds the first parent of an element that has a transformed property defined