codility.js

// task1
function solution(A) {
  var pos = 0;
  var len = 0;
  while(A[pos] !== -1){
    len++;
    pos = A[pos];
  }
  return len;
}
console.log(solution([1, -1, -1, 3, 2]));//-1
console.log(solution([1, 4, -1, 3, 2])); // 3
console.log(solution([1, 4, 3, -1, 2])); // 4