App.js

class PlainText extends React.Component {

    state = {
        value: Plain.deserialize('This is editable plain text, just like a <textarea>!')
    }

    onChange = ({ value }) => {
        this.setState({ value });
    }

    render() {
        return (
            <div className="editor">
              <Editor
                placeholder="Enter some plain text..."
                value={this.state.value}
                onChange={this.onChange}
                />
            </div>
        );
    }

}