JAVASCRIPT
Validate 24-Hour Time Format (HH:MM or HH:MM:SS)
Validate if a string represents a valid 24-hour time (HH:MM or HH:MM:SS) using a precise regular expression for robust input checks.
function isValid24HourTime(timeString) {
const regex = /^(?:2[0-3]|[01]?[0-9]):(?:[0-5]?[0-9])(?::(?:[0-5]?[0-9]))?$/;
return regex.test(timeString);
}
// Example usage:
// console.log(isValid24HourTime('14:30'));
// console.log(isValid24HourTime('09:05:22'));
// console.log(isValid24HourTime('25:00'));
// console.log(isValid24HourTime('10:65'));
// console.log(isValid24HourTime('1:2'));
How it works: This JavaScript function validates a string to ensure it adheres to a strict 24-hour time format (HH:MM or HH:MM:SS). The regular expression `^(?:2[0-3]|[01]?[0-9]):(?:[0-5]?[0-9])(?::(?:[0-5]?[0-9]))?$` precisely matches hours from 00-23, minutes from 00-59, and an optional seconds part also from 00-59. The `^` and `$` anchors ensure the entire string must match the pattern, preventing partial matches.