react-time-input/src/validate.js

A simple react component for select time in format HH:mm

export const isValid = (val) => {
    const regexp = /^\d{0,2}?\:?\d{0,2}$/;

    const [hoursStr, minutesStr] = val.split(':');

    if (!regexp.test(val)) {
        return false;
    }

    const hours = Number(hoursStr);
    const minutes = Number(minutesStr);

    const isValidHour = (hour) => Number.isInteger(hour) && hour >= 0 && hour < 24;
    const isValidMinutes = (minutes) => (Number.isInteger(minutes) && hours >= 0 && hours < 24) || Number.isNaN(minutes);

    if (!isValidHour(hours) || !isValidMinutes(minutes)) {
        return false;
    }

    if (minutes < 10 && Number(minutesStr[0]) > 5) {
        return false;
    }

    const valArr = val.indexOf(':') !== -1
        ? val.split(':')
        : [val];

    // check mm and HH
    if (valArr[0] && valArr[0].length && (parseInt(valArr[0], 10) < 0 || parseInt(valArr[0], 10) > 23)) {
        return false;
    }

    if (valArr[1] && valArr[1].length && (parseInt(valArr[1], 10) < 0 || parseInt(valArr[1], 10) > 59)) {
        return false;
    }

    return true;
}