ok.js

result = ((arr) => {
  let biggest = 0
  let second_biggest = 0
  
  for(let i = 0; i < arr.length; i++) {
    if (arr[i] > biggest) {
      second_biggest = biggest
      biggest = arr[i]
    } else if (arr[i] > second_biggest && arr[i] < biggest) {
      second_biggest = arr[i]
    }
  }
  return second_biggest
})


let arr = [7,2,3,4,5,5,1]
console.log(result(arr))