Validation .isValid() doesn't work always

The .isValid() validation doesn’t function correctly under the following condition:

• When the the day part is 31 for a month which didn’t have 31 days.

Some instances where .isValid() returns true for a date that is invalid:

• dayjs().isValid('1995-02-31')
• dayjs().isValid('1995-03-31')
• dayjs().isValid('1995-04-31')
• dayjs().isValid('1995-06-31')
• dayjs().isValid('1995-09-31')
• dayjs().isValid('1995-11-31')

[huberzeljko]

Is this an option to validate if date exist?

function validate(date, format) {
  return dayjs(date, format).format(format) === date;
}

validate('2019/02/31', 'YYYY/MM/DD') // false

[wmonecke]

Why is this still closed? This issue cost me at least 4 hours because it is still broken.