@material-ui/popper.js/src/utils/getOppositeVariation.js

A fork of popper.js to avoid the deprecation warnings: https://github.com/mui-org/material-ui/issues/19358.

/**
 * Get the opposite placement variation of the given one
 * @method
 * @memberof Popper.Utils
 * @argument {String} placement variation
 * @returns {String} flipped placement variation
 */
export default function getOppositeVariation(variation) {
  if (variation === 'end') {
    return 'start';
  } else if (variation === 'start') {
    return 'end';
  }
  return variation;
}