filter_object_async_without_conductor.js

const obj = { books: 10, ruler: 1, pencils: 5 }
const isEven = x => Promise.resolve(x % 2 === 0)
const result = await Promise
  .all(Object.values(obj).map(isEven))
  .then(results => Object.keys(obj).reduce((acc, key, index) => {
    if (results[index]){
      acc[key] = obj[key]
    }
    return acc
  }, {}) // { books: 10 }