@atlaskit/adf-schema/dist/es2019/schema/marks/subsup.js

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

import { FONT_STYLE } from '../groups';

/**
 * @name subsup_mark
 */

function getAttrFromVerticalAlign(node) {
  if (node.style.verticalAlign) {
    const type = node.style.verticalAlign.slice(0, 3);
    if (type === 'sub' || type === 'sup') {
      return {
        type
      };
    }
  }
  return false;
}
export const subsup = {
  inclusive: true,
  group: FONT_STYLE,
  attrs: {
    type: {
      default: 'sub'
    }
  },
  parseDOM: [{
    tag: 'sub',
    attrs: {
      type: 'sub'
    }
  }, {
    tag: 'sup',
    attrs: {
      type: 'sup'
    }
  }, {
    // Special case for pasting from Google Docs
    // Google Docs uses vertical align to denote subscript and super script
    tag: 'span',
    style: 'vertical-align=super',
    getAttrs: node => getAttrFromVerticalAlign(node)
  }, {
    tag: 'span',
    style: 'vertical-align=sub',
    getAttrs: node => getAttrFromVerticalAlign(node)
  }],
  toDOM(mark) {
    return [mark.attrs.type];
  }
};