@popperjs/core/lib/utils/getOppositePlacement.js.flow

Tooltip and Popover Positioning Engine

// @flow
import type { Placement } from '../enums';

const hash = { left: 'right', right: 'left', bottom: 'top', top: 'bottom' };

export default function getOppositePlacement(placement: Placement): Placement {
  return (placement.replace(
    /left|right|bottom|top/g,
    matched => hash[matched]
  ): any);
}