app.js

process.stdin.resume();
process.stdin.setEncoding("utf8");
let now = new Date(Date.now());
let year = now.getFullYear();
console.log("How old are you?");
process.stdin.on("data", integer => {
  if (typeof integer === "number" && Number.isInteger(integer)) {
    if (integer <= 99) {
      let birthYear = year - integer;
      console.log(`You were born in ${birthYear}`);
      process.exit();
    } else {
      console.log("Nobody's this old");
      process.exit();
    }
  } else {
    console.log("Age must be an integer");
    process.exit();
  }
});