// Validates dates in YYYY-MM-DD format, checking for valid month (01-12) and day (01-31).
// It does not validate for leap years or days specific to certain months (e.g., 31 for Feb).
const dateRegex = /^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12][0-9]|3[01])$/;

function isValidYYYYMMDDDate(dateString) {
  return dateRegex.test(dateString);
}

// Example usage:
// console.log(isValidYYYYMMDDDate('2023-10-26')); // true
// console.log(isValidYYYYMMDDDate('2023-02-30')); // true (regex doesn't catch invalid day for month)
// console.log(isValidYYYYMMDDDate('2023-13-01')); // false
// console.log(isValidYYYYMMDDDate('23-10-26'));  // false