Controlled Inputs in React Explained (Forms, State & preventDefault) In React, when an input’s value is linked to a state variable, the input becomes controlled by React. That means every change updates the state, and React automatically updates the UI — no manual DOM handling needed. In this lesson, I explain how controlled components work, why they’re essential in single-page applications, and why preventDefault() is critical when submitting forms. Instead of reloading the page, we capture the

8 Best React.js Projects for Beginners to learn in 2025