UncontrolledFormInput.component.js

class UncontrolledFormInput extends React.Component {
  constructor(props) {
    super(props);
    this.inputField = React.createRef();
    this.handleChange = this.handleChange.bind(this);
    this.state = { value: "Glad" };
  }

  handleChange(evt) {
    this.setState({ value: this.inputField.current.value });
  }

  render() {
    return (
      <div>
        <h1>Hello {this.state.value}!</h1>
        {/* Attach the created ref: this.inputField */}
        <input type="text" ref={this.inputField} defaultValue={this.state.value} onChange={this.handleChange} placeholder="Enter your name" />
      </div>
    )
  }
}