react-input-time/src/utils/getNewValue.js

A simple, yet customizable, React component for time selection.

import isValid from './isValid';

const getNewValue = (prevValue, newValue) => {
    if (newValue === prevValue || !isValid(newValue)) {
        return '';
    }

    if (newValue.length === 2 && prevValue.length !== 3 && !newValue.includes(':')) {
        newValue = `${newValue}:`;
    }

    if (newValue.length === 2 && prevValue.length === 3) {
        newValue = newValue.slice(0, 1);
    }

    return newValue;
};

export default getNewValue;