Danil Sitdikov

const removeNonUnique = array => {
  const dict = array.reduce((acc,it) => {
    if(acc[it]){
      acc[it] = {...acc[it], count: acc[it].count + 1}
      return acc
    }
    acc[it] = {value: it, count: 1}
    return acc
  }, {})

  return Object.keys(dict).filter((it) => dict[it].count < 2)
}