vant/src/count-down/utils.ts

import { padZero } from '../utils';
import { CurrentTime } from '@vant/use';

export function parseFormat(format: string, currentTime: CurrentTime): string {
  const { days } = currentTime;
  let { hours, minutes, seconds, milliseconds } = currentTime;

  if (format.indexOf('DD') === -1) {
    hours += days * 24;
  } else {
    format = format.replace('DD', padZero(days));
  }

  if (format.indexOf('HH') === -1) {
    minutes += hours * 60;
  } else {
    format = format.replace('HH', padZero(hours));
  }

  if (format.indexOf('mm') === -1) {
    seconds += minutes * 60;
  } else {
    format = format.replace('mm', padZero(minutes));
  }

  if (format.indexOf('ss') === -1) {
    milliseconds += seconds * 1000;
  } else {
    format = format.replace('ss', padZero(seconds));
  }

  if (format.indexOf('S') !== -1) {
    const ms = padZero(milliseconds, 3);

    if (format.indexOf('SSS') !== -1) {
      format = format.replace('SSS', ms);
    } else if (format.indexOf('SS') !== -1) {
      format = format.replace('SS', ms.slice(0, 2));
    } else {
      format = format.replace('S', ms.charAt(0));
    }
  }

  return format;
}