const payPad = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [null, 0, null]];
function getIndexes(n) {
  let arrayIndex = Math.floor((n - 1) / 3);
  let numberIndex = n - 1 - 3 * arrayIndex;
  return [arrayIndex, numberIndex];
}

function getPossibilies([arrayIndex, numberIndex]) {
  const resullt = [];
  for (let i = 0; i <= 3; i++) {
    if (arrayIndex - i === 0) {
      for (let j = 0; j < 3; j++) {
        if (Math.abs(numberIndex - j) < 2) {
          resullt.push(payPad[i][j]);
        }
      }
    }
    if (Math.abs(i - arrayIndex) == 1) {
      resullt.push(payPad[i][numberIndex]);
    }
  }
  return resullt;
}

function getPins(observed) {
  const result = [];
  const possibilities = [];
  observed.split("").forEach(n => {
    possibilities.push(getPossibilies(getIndexes(Number(n))));
  });
  for (let i = 0; i < possibilities[0].length; i++) {
    let str = `${possibilities[0][i]}`;
    for (let j = 1; j < possibilities.length; j++) {
      for (let k = 0; k < possibilities[j].length; k++) {
        str += possibilities[j][k];
        if (str.length == observed.length) {
          result.push(str);
          str = `${possibilities[0][i]}`;
        }
      }
    }
  }
  return result;
}

getPins("11");