index.js

// @flow
import * as React from "react";
import { Editor, EditorState } from "draft-js";

type Props = {
  onChangeText?: (text: string) => void,
  onSubmit?: void => void
};

type State = {
  editorState: EditorState
};

export default class CustomEditor extends React.Component<Props, State> {
  static defaultProps = {
    onChangeText: () => {},
    onSubmit: () => {}
  };

  state = { editorState: EditorState.createEmpty() };

  onChange = (editorState: EditorState) => {
    const { onChangeText } = this.props;
    const text = editorState.getCurrentContent().getPlainText();

    this.setState({ editorState }, () => {
      if (onChangeText) onChangeText(text);
    });
  };

  handleReturn = (event: SyntheticKeyboardEvent<*>) => {
    const { onSubmit } = this.props;

    if (event.shiftKey) return "not-handled";
    if (onSubmit) onSubmit();
    return "handled";
  };

  render() {
    const { editorState } = this.state;

    return (
      <Editor
        editorState={editorState}
        onChange={this.onChange}
        handleReturn={this.handleReturn}
      />
    );
  }
}