What is Controlled Component?

A Controlled Component is one that takes its current value through state and notifies changes through callbacks like onChange.

For example below, I log the name when it is submitted, with controlled component:

See the Pen pVBwwa by Bunlong (@Bunlong) on CodePen.

<input> form element takes its current value through this.state.value. handleChange runs on every keystroke to update this.state.value, the displayed value will update as the user types.