How can I implement validation in my Formik forms?

How can I implement validation in my Formik forms?

You can use the validate prop in Formik to define a validation function. This function should return an object with errors.

Can you show me an example of a validation function?

Sure! Here's a simple example:

const validate = values => {
  const errors = {};
  if (!values.email) {
    errors.email = 'Required';
  } else if (!/\S+@\S+\.\S+/.test(values.email)) {
    errors.email = 'Invalid email address';
  }
  return errors;
};

What about using Yup for validation?

Yup is a great library for schema-based validation. You can define a schema and pass it to Formik's validationSchema prop.

Can you provide a quick example of using Yup with Formik?

Absolutely! Here's a quick example:

import * as Yup from 'yup';

const validationSchema = Yup.object().shape({
  email: Yup.string().email('Invalid email').required('Required'),
});

<Formik
  initialValues={{ email: '' }}
  validationSchema={validationSchema}
  onSubmit={values => { /* handle submit */ }}
>
  {/* form components */}
</Formik>