@atlaskit/editor-common/dist/es2019/utils/dedupe.js

A package that contains common classes and components for editor and renderer

export function dedupe(list = [], iteratee = p => p) {
  /**
              .,
    .      _,'f----.._
    |\ ,-'"/  |     ,'
    |,_  ,--.      /
    /,-. ,'`.     (_
    f  o|  o|__     "`-.
    ,-._.,--'_ `.   _.,-`
    `"' ___.,'` j,-'
      `-.__.,--'
    Gotta go fast!
  */

  const seen = new Set();
  list.forEach(l => seen.add(iteratee(l)));
  return list.filter(l => {
    const it = iteratee(l);
    if (seen.has(it)) {
      seen.delete(it);
      return true;
    }
    return false;
  });
}