jtBaseApp/node_modules/@popperjs/core/lib/utils/uniqueBy.js.flow

// @flow

export default function uniqueBy<T>(arr: Array<T>, fn: T => any): Array<T> {
  const identifiers = new Set();

  return arr.filter(item => {
    const identifier = fn(item);

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