@atlaskit/adf-schema/dist/es2019/schema/marks/font-size.js

Shared package that contains the ADF-schema (json) and ProseMirror node/mark specs

import { fontSize as fontSizeFactory } from '../../next-schema/generated/markTypes';
const allowedSizes = ['small'];

/**
 * @name fontSize_mark
 */

export const fontSize = fontSizeFactory({
  parseDOM: [{
    tag: 'div.fabric-editor-font-size',
    getAttrs(dom) {
      // eslint-disable-next-line @atlaskit/editor/no-as-casting
      const fontSize = dom.getAttribute('data-font-size');
      return {
        fontSize: allowedSizes.indexOf(fontSize || '') === -1 ? 'small' : fontSize
      };
    }
  }],
  toDOM(mark) {
    return ['div', {
      class: 'fabric-editor-block-mark fabric-editor-font-size',
      'data-font-size': mark.attrs.fontSize
    }, 0];
  }
});