Handling Form Submission and Validation
Learn how to handle form submissions and validate user input in React 19 using controlled components and declarative validation logic.
We'll cover the following...
Forms are only as good as the data they capture. A single incorrect email or weak password can break the user experience or cause errors downstream. In plain JavaScript, developers validate inputs by manually checking DOM elements and updating error messages — often resulting in duplicated, hard-to-maintain logic.
React changes this: since inputs are controlled by React state, validation can happen declaratively. You define validation rules in your component, and React automatically re-renders the UI to reflect the validation state — no manual DOM manipulation required.
Declarative validation flow
In React, form validation integrates directly into our component’s state management.
Here’s how the flow works:
User types into the input fields, which update the React state (
formData). ...