코테연습, 배열/중복

let arr = [1,2,3,3,3,3,4,5,4]

let answer = arr.reduce((array, value) =>{
  array[value] = (array[value] || 0) + 1 ;
  return array;
},{})

answer= Object.values(answer);
let final = answer.filter(e=> e>1);
console.log(final)