How can I implement custom validation in React?

How can I implement custom validation in React?

You can create custom validation in React by using controlled components and defining your validation logic in the state.

Can you show me an example of a custom validation function?

Sure! Here's a simple example:

const validateEmail = (email) => {
  const re = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;
  return re.test(String(email).toLowerCase());
};

You can call this function in your form submission handler.

What if I want to validate multiple fields?

You can manage multiple fields by keeping an object in your state that holds the values and their corresponding error messages. Validate each field in your submission handler.

Are there any libraries that can help with validation?

Yes, libraries like Formik and Yup are great for handling forms and validation in React. They simplify the process significantly.