ReactJS和DraftJS，如何动态改变字体大小？

import React, { Component } from 'react';
import { Editor, EditorState, ContentState } from 'draft-js';

class MyEditor extends Component {
  constructor(props) {
    super(props);
    this.state = {
      editorState: EditorState.createEmpty(),
      fontSize: '16px'
    };
  }

  handleFontSizeChange = (event) => {
    const fontSize = event.target.value;
    this.setState({ fontSize });
  }

  handleEditorChange = (editorState) => {
    this.setState({ editorState });
  }

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

    const contentState = editorState.getCurrentContent();
    const blockMap = contentState.getBlockMap();

    blockMap.forEach((contentBlock) => {
      const newContentState = contentState.merge({
        blockMap: contentState.getBlockMap().set(
          contentBlock.getKey(),
          contentBlock.setInlineStyle('FONT_SIZE', fontSize)
        ),
      });
      const newEditorState = EditorState.push(editorState, newContentState, 'change-block-data');
      this.handleEditorChange(newEditorState);
    });

    return (
      <div>
        <select value={fontSize} onChange={this.handleFontSizeChange}>
          <option value="12px">12</option>
          <option value="16px">16</option>
          <option value="20px">20</option>
        </select>
        <Editor editorState={editorState} onChange={this.handleEditorChange} />
      </div>
    );
  }
}

export default MyEditor;