jsDay1

function extractNum(str) {
  const match = str.match(/\d+/);
  return parseInt(match[0], 10);
}

function calcSum(arr) {
  const flatArr = arr.flat(2);
  let sum = 0;

  flatArr.forEach((item) => {
    if (typeof item === "string") {
      sum += extractNum(item);
    } else {
      sum += item;
    }
  });

  return sum;
}

console.log(calcSum([1, 2, "3x"]));
console.log(calcSum([1, 2, "x3"]));
console.log(calcSum([1, [1, [2]], 2]));