Email Validation with React Hook Forms

What is React Hook Form?

A quick refresher never hurts! Let’s briefly go over the basics of React Hook Form (RHF). 

RHF is a lightweight library for building performant, flexible, and scalable forms in React. It leverages React Hooks and uncontrolled components to manage form data, streamline validation, handle submissions, and provide user feedback.

By using uncontrolled inputs and minimizing re-renders, RHF offers several advantages over other form solutions. For instance:

• Optimized performance. RHF relies on uncontrolled components under the hood, which significantly reduces re-renders. This leads to snappier forms and simpler logic, especially when dealing with large or dynamic inputs.
• Built-in validation. It supports a wide range of verification scenarios, including native HTML validation, complex schema validation with Yup, Zod, and others, and custom rules.
• Ease of use. React Forms’ intuitive API and minimal boilerplate help you implement form logic without cluttering your components with state logic. You can get forms up and running quickly while keeping your codebase clean.
• Flexibility. This library doesn’t enforce a specific pattern. It enables you to easily add dynamic fields, conditionally render inputs, or build multi-step forms, without rewriting core logic. All of this also makes RHF highly scalable.
• TypeScript support. RHF provides strong typings for inputs, error states, and validation logic, which will help you catch issues early and enforce type safety across your form code.

In short, React Hook Forms allows you to write cleaner, faster, and more scalable form logic. This makes it an ideal choice for implementing email validation and efficiently managing complex form state in modern React apps.

Basic Email Validation with React Hook Forms

Here’s our step-by-step guide to implementing basic email validation using React Hook Forms. For more advanced techniques, jump straight to the next section. However, if you’re in for the fundamentals of React Form validation, let’s get down to business.

1. To implement basic email validation with React Hook Form, first, we’ll use npm or yarn to install the React Hook Form library.

2. Once the library is installed, we’ll set up the form using the hook useForm(). This hook is used to handle form behavior and will allow our app to capture user inputs, manage errors, and validate fields. To set it up:
   
   1. Import the hooks react and useForm. react will create and render the component, while useForm will provide us with the tools to manage the form.

2. Create a function component that defines the form. Here, it will be defined as SignUpForm().

3. Call useForm() to get form tools such as register, handleSubmit, and errors.

4. Define what will happen when the form is submitted. Here, the function onSubmit will run only if every field passes validation.

5. Create the <form> element to wrap your inputs. Use the function onSubmit={handleSubmit(onSubmit)} to ensure that RHF will first validate the input and run onSubmit(data) only if it’s valid.

Always wrap onSubmit with handleSubmit, otherwise the form may bypass validation entirely.

6. Export the component to make your SignUpForm available.

3. After setting up the form, implement register() to connect the input and apply validation rules. Regarding the latter, as this is a simple validation form, we’ll use a simple regular expression pattern (regex).

4. To follow best validation practices, we’ll set the form to conditionally render feedback, using the errors object from formState.

That’s it!  You've just implemented basic email validation using React Hook Form. Want to take it further? You can add schema-based validation with Yup or Zod, or integrate a third-party email validation API to verify email authenticity in real time.

Advanced Validation with RHF

Basic email validation is a great start, but it won’t fully protect your app from typos, malformed inputs, or fake addresses. So, what can you do? Well, it’s time to go beyond the basics.

Here are some actionable techniques to strengthen email validation using React Hook Form:

• Using a more robust regex. The basic regex from the previous section works for many use cases, but it can still allow invalid formats like john@.com, @gmail, me@localhost, or email@domain..com. To handle these edge cases, implement a stricter regex pattern, such as this one:

• Custom validation function. React Hook Form supports custom validation logic beyond regex. Using the validate property, you can enforce business-specific rules and enhance security.  For example, here’s how to reject specific email domains:

• Conditional validation. Thanks to RHF’s flexibility, you can dynamically enforce rules based on user interaction.

Let’s say your sign-up form includes an “Admin” checkbox. If checked, the user must register with a corporate email (@yourcompany.com only). Otherwise, any valid email is fine.

Here’s how that logic might look:

These techniques will help you implement complex validation rules, enhancing both the user’s experience, your app’s security, and complying with business regulations, if necessary. 

However, keep in mind that email validation with React Hook Forms is client-side validation, which means that it will have some limitations, regardless of its complexity. 

Limitations of Client-Side Validation

React Hook Form gives you flexible, powerful tools for validating emails on the client side. But relying solely on them won’t guarantee that the data you collect is fully trustworthy. Why not? Because, as mentioned earlier, client-side validation has significant limitations:

• Bypassable. As client-side validation runs in the browser, users can easily bypass it by disabling JavaScript or using browser developer tools. 
• Limited to format validation. Client-side libraries, in general, can only check the format of the email address and enforce simple conditions. It doesn’t verify if the address exists, if it’s already in your database, or if it’s deliverable.
• Data inaccuracy. Even if RHF flags invalid formats or catches typos, it won’t catch invisible characters, leading/trailing spaces, or copy-paste errors unless you sanitize inputs manually.

Think of React Hook Forms as a first filter that improves user experience and reduces failed API calls, but not as a source of data you can fully rely on. The good news? Limitations of client-side validation can be easily solved by combining RHF with server-side email validation. 

Robust Email-Verification: Email Validation APIs

There are several ways to implement server-side email validation, from simple regex checks to double opt-in verification. But one of the most robust and scalable options is integrating a dedicated email validation API, like Abstract’s.

These APIs offer a robust solution for confirming email deliverability and detecting potentially invalid or risky addresses. Key benefits include:

• Real-time validation. Quality email validation APIs instantly verify if an email address is valid, providing accurate and up-to-date results. Some APIs also send double-opt-in emails for more reliable results.
• Comprehensive data. While React Hook Form can validate an email’s format, APIs like Abstract’s go further. They return detailed JSON responses with information such as deliverability status, email provider, format validity, and risk flags.
• Improved deliverability. Email APIs perform deep checks, including syntax validation, MX record lookups, and SMTP verification. This means you’ll know whether the domain exists and can receive mail, the mailbox is reachable, and if the address is safe to send to. 
• Fraud prevention. By identifying disposable addresses, catch-all domains, and suspicious patterns, validation APIs help you block spam accounts, fake signups, and potential fraud before they hit your system.

Server-Side Verification, Step-by-Step

Were you wondering how to integrate an email validation API into the logic of your React Hook Forms? The procedure is quite simple. Or, at least, it’s with Abstract’s Email Validation API.

The initial steps are the same as we followed for implementing basic email validation with RHF on the client-side. However, we’ll also use the onSubmit function to include a fetch request that sends the email address to a backend route, only if it passes RHF validation. 

Once the data is there, the backend will issue a GET request to Abstract’s API. The API will verify the email and return a response indicating whether it is valid or not. If the address is safe and deliverable, our app will proceed with the sign-up.

Best Practices for Email Validation 

Want a clean, active contact list that keeps your bounce rate low and boosts deliverability? Need to ensure the security of the data your app handles? Looking to provide a great user experience? Implementing email validation with React Hook Form can help you achieve all of this, especially when paired with best practices for verifying emails. Some of these are:

• Using React Hook Form for client-side validation to improve user experience and provide immediate feedback. Implement a robust regex or built-in pattern rules for a more thorough verification, preventing unnecessary server requests.

• Implement server-side validation to ensure data accuracy and security, using dedicated APIs, such as the Abstract API email validator.
• Normalise and sanitize inputs before sending them to the API for further validation. Trim whitespace and convert to lowercase if your system treats emails as case-insensitive.

• Provide clear and informative error messages to users. Let them know what’s wrong with the input and how they can fix it.
• Handle API errors gracefully, wrapping API calls in try/catch, and providing fallback messages in case of network failures, rate limit hits, or unexpected responses.

These practices will help you improve email deliverability, reduce invalid signups, and build user trust, enhancing your app’s performance and maximizing the use of your resources..

Smarter Validation for Stronger Apps

Email validation with React Hook Form blends user experience, performance optimization, and basic security into a clean, flexible, and intuitive interface. 

It’s a must-have for any well-built React app. But relying on client-side validation alone isn’t always enough to ensure accuracy or prevent bad data from slipping through.

By combining React Hook Form on the frontend with a trusted server-side API like Abstract, you get the best of both worlds: a fast, responsive UI backed by real-time verification, fraud prevention tools, and deliverability insights.

Build smarter forms and power your apps with the right tools. With AbstractAPI, create stronger, more reliable applications, one verified email at a time.

‍