semi-design/packages/semi-foundation/datePicker/_utils/isBefore.ts

import { isBefore as dateFnsIsBefore, parseISO } from 'date-fns';
import isString from '../../utils/isString';

export default function isBefore(date: Date | string, dateToCompare: Date | string) {
    const dayOne = isString(date) ? parseISO(date) : date;
    const dayTwo = isString(dateToCompare) ? parseISO(dateToCompare) : dateToCompare;
    return dateFnsIsBefore(dayOne, dayTwo);
}