How can I implement async validation with Yup?

How can I implement async validation with Yup?

You can use the test method in Yup to create an asynchronous validation function. Would you like an example?

Yes, please provide an example of async validation.

Sure! Here's a simple example:

import * as Yup from 'yup';

const schema = Yup.object().shape({
  email: Yup.string()
    .email('Invalid email')
    .test('checkEmail', 'Email already exists', async value => {
      const response = await fetch(`/api/check-email?email=${value}`);
      const data = await response.json();
      return !data.exists;
    }),
});

This checks if the email already exists in your database.

What if I want to validate a username instead?

You can use a similar approach. Just replace the email validation with username validation in the test method.