api/sample/dev/talk/bundle/popper-2.11.8/esm/utils/uniqueBy.js

export default function uniqueBy(arr, fn) {
  var identifiers = new Set();
  return arr.filter(function (item) {
    var identifier = fn(item);

    if (!identifiers.has(identifier)) {
      identifiers.add(identifier);
      return true;
    }
  });
}