dayjsを使った日付のバリデート

validateDate.test.ts

import { validateDate } from "./validateDate";

describe("有効な日付のテスト", () => {
  it.each(["2021/01/01", "2021/12/31", "2021/02/01", "2000/02/29"])(
    "%sは正しい日付である",
    (date) => {
      expect(validateDate(date, "YYYY/MM/DD")).toBe(true);
    }
  );

  it.each(["2021/01/999", "2021/02/29", "2021/2/1", "あああ"])(
    "%sは正しい日付ではない",
    (date) => {
      expect(validateDate(date, "YYYY/MM/DD")).toBe(false);
    }
  );
});

validateDate.ts

import dayjs from "dayjs";

/**
 * 日付が正しいかをチェックする
 */
export const validateDate = (date: string, format: string): boolean => {
  return dayjs(date, format).format(format) === date;
};

// 参考 https://qiita.com/kubotak/items/3bbde3c976606493060d

詳細
https://twitter.com/tonkotsuboy_com/status/1419568078090690560