React 19 Forms & Controlled Components | Build Real Input Forms | React 19 Day 6

React 19 Forms & Controlled Components | Build Real Input Forms | React 19 Day 6

In Day 6 of the React 19 series, you will learn how real applications handle user input using forms and controlled components.

Every modern app depends on user input — login, signup, search, payments, and feedback. But HTML forms manage their own data, which makes it hard for React to keep your UI predictable and bug free. This is why React uses controlled components.

In this lesson, you will understand how React takes full control of input fields by connecting them to state. You will see how every keystroke updates state, and how that state drives what appears in the UI.

You will learn how to:
Build controlled input fields
Connect input values to React state
Handle onChange events correctly
Submit forms without page refresh
Capture and process user data
Build login and signup style forms

We will start with a single controlled input, then move to real forms with multiple fields like email and password. After that, you will learn the industry pattern for large forms, where one state object manages all input fields using a single change handler.

You will also learn why preventDefault is required when submitting a form and how React collects data without reloading the page.

This lesson follows modern React 19 best practices and prepares you for advanced features like Form Actions and server powered forms.

Common mistakes you will avoid:
Inputs not connected to state
Mixing controlled and uncontrolled inputs
Page refresh on submit
Direct state mutation
Broken or unpredictable form behavior

By the end of this video, you will be able to build real world forms that power login systems, signup pages, dashboards, and admin panels.

Homework:
Build a signup form with name, email, and password, and log the data when the user submits the form.

Next in the series: useEffect — fetching data and running side effects in React 19.