validate-cron-expression.js

function validateCronExpression(input) {
  const segment = '(\\*|(T|\\*\\/[1-9][0-9]*|(T)(-(T))?)(,(T|\\*\\/[1-9][0-9]*|(T)(-(T))?))*)';
  const minute = segment.replaceAll('T', '[0-5]?[0-9]');
  const hour = segment.replaceAll('T', '[0-1]?[0-9]|2[0-3]');
  const dayOfMonth = segment.replaceAll('T', '[1-9]|[12][0-9]|3[01]');
  const month = segment.replaceAll('T', '[1-9]|1[0-2]');
  const dayOfWeek = segment.replaceAll('T', '[0-6]');
  const cronRegex = new RegExp(`^${minute}\\s+${hour}\\s+${dayOfMonth}\\s+${month}\\s+${dayOfWeek}$`);
  return cronRegex.test(input);
}