code: function getReferenceOffsets(state, popper, reference, fixedPosition = null) {
    const commonOffsetParent = fixedPosition ? getFixedPositionOffsetParent(popper) : findCommonOffsetParent(popper, reference);
    return getOffsetRectRelativeToArbitraryNode(reference, commonOffsetParent, fixedPosition);
  }
docs: Get offsets to the reference element
  @method
  @memberof Popper.Utils
  @param {Object} state
  @param {Element} popper - the popper element
  @param {Element} reference - the reference element (the popper will be relative to this)
  @param {Element} fixedPosition - is in fixed position mode
  @returns {Object} An object containing the offsets which will be applied to the popper