uniqueBy

uniqueBy.js

const uniqBy = (arr, predicate) => {
  if (!Array.isArray(arr)) { return []; }

  const cb = typeof predicate === 'function' ? predicate : (o) => o[predicate];

  const pickedObjects = arr
    .filter(item => item)
    .reduce((map, item) => {
        const key = cb(item);

        if (!key) { return map; }

        return map.has(key) ? map : map.set(key, item);
    }, new Map())
    .values();

  return [...pickedObjects];
};