Zalando - Coding Test

test.2.js

'use strict';

/* global CustomError, getLikedBrands, getTopBrandsForGender */

function solution(U, N) {
    return new Promise((resolve, reject) => {

        // Uniq function
        const uniq = list => Array.from( new Set(list) )
        
        getLikedBrands(U.id).then(likedBrands => likedBrands.length >= N
            // If liked brands are enough
            ? resolve(
                likedBrands
                    .slice(0, N)
                    .map(i => i.name)
            )

            // If not enough, get more brands
            : getTopBrandsForGender(U.gender).then(topBrands => {

                // Concat and unify brands list
                const allBrands = uniq(
                    [...likedBrands, ...topBrands]
                    .map(i => i.name)
                )

                allBrands.length >= N
                    // If all brands are enough
                    ? resolve(allBrands.slice(0, N))
                    // If still not enough
                    : reject(new CustomError('Not enough data'))
            })
        )
    });
}

https://gist.github.com/marco-souza/a6f7c1af8a738ed14eac3e4d85e3d262