Convert HTML to RTF

HTML

<div>
     <h2>Rendered HTML Input</h2>

    <div id="test-input-rendered">
<div><strong>TESTE EDUARDO</strong></div><div><br></div><div><strong>Laudioiodsoidiosiudsuiodusuoduois[]</strong></div><div><strong>opsdksdkodkspokpodskpods</strong></div><div><strong>opksdkpodskopdskopkodps</strong></div><div><strong>sodkpskopkpds</strong></div><ul><li><strong>sddsdsdsdsdssd</strong></li><li><strong>sddsdsdsdsds</strong></li><li><strong>sddsdsdsds</strong></li><li><strong>dsdsdssd</strong></li><li><br></li></ul><div class="ql-align-center"><strong>Teste estetsgetstes</strong></div>
    </div>
</div>
<div>
     <h2>HTML Input</h2>

    <textarea id="test-input"></textarea>
</div>
<div>
     <h2>RTF Output</h2>

    <textarea id="test-output"></textarea>
</div>

CSS

textarea {
    width: 500px;
    height: 150px;
    font-family: Consolas, Monaco, Lucida Console, Liberation Mono, DejaVu Sans Mono, Bitstream Vera Sans Mono, Courier New, monospace;
    font-size: 100%;
}
textarea#test-output {
    height: 500px;
}

JavaScript

function convertHtmlToRtf(html) {
      if (!(typeof html === "string" && html)) {
          return null;
      }

      var tmpRichText, hasHyperlinks;
      var richText = html;

      // Singleton tags
      richText = richText.replace(/<(?:hr)(?:\s+[^>]*)?\s*[\/]?>/ig, "{\\pard \\brdrb \\brdrs \\brdrw10 \\brsp20 \\par}\n{\\pard\\par}\n");
      richText = richText.replace(/<(?:br)(?:\s+[^>]*)?\s*[\/]?>/ig, "{\\pard\\par}\n");

      // Empty tags
      richText = richText.replace(/<(?:p|div|section|article)(?:\s+[^>]*)?\s*[\/]>/ig, "{\\pard\\par}\n");
      richText = richText.replace(/<(?:[^>]+)\/>/g, "");

      // Hyperlinks
      richText = richText.replace(
          /<a(?:\s+[^>]*)?(?:\s+href=(["'])(?:javascript:void\(0?\);?|#|return false;?|void\(0?\);?|)\1)(?:\s+[^>]*)?>/ig,
          "{{{\n");
      tmpRichText = richText;
      richText = richText.replace(
          /<a(?:\s+[^>]*)?(?:\s+href=(["'])(.+)\1)(?:\s+[^>]*)?>/ig,
          "{\\field{\\*\\fldinst{HYPERLINK\n \"$2\"\n}}{\\fldrslt{\\ul\\cf1\n");
      hasHyperlinks = richText !== tmpRichText;
      richText = richText.replace(/<a(?:\s+[^>]*)?>/ig, "{{{\n");
      richText = richText.replace(/<\/a(?:\s+[^>]*)?>/ig, "\n}}}");

      // Start tags
      richText = richText.replace(/<(?:b|strong)(?:\s+[^>]*)?>/ig, "{\\b\n");
      richText = richText.replace(/<(?:i|em)(?:\s+[^>]*)?>/ig, "{\\i\n");
      richText = richText.replace(/<(?:u|ins)(?:\s+[^>]*)?>/ig, "{\\ul\n");
      richText = richText.replace(/<(?:strike|del)(?:\s+[^>]*)?>/ig, "{\\strike\n");
      richText = richText.replace(/<sup(?:\s+[^>]*)?>/ig, "{\\super\n");
      richText = richText.replace(/<sub(?:\s+[^>]*)?>/ig, "{\\sub\n");
      richText = richText.replace(/<(?:p|div|section|article)(?:\s+[^>]*)?>/ig, "{\\pard\n");

      // End tags
      richText = richText.replace(/<\/(?:p|div|section|article)(?:\s+[^>]*)?>/ig, "\n\\par}\n");
      richText =...