function removeOtherTags(node) {
  var domList = ['P', 'B', 'U', 'I', 'STRIKE', 'FONT', 'UL', 'LI', 'OL', 'SPAN', 'STRONG', 'EM', 'H1', 'H2', 'H3', 'H4', 'H5', 'H6'];
  for (var i = 0; i < node.childNodes.length; i++) {
    var childNode = node.childNodes[i];
    if (childNode.nodeType === Node.ELEMENT_NODE) {
      if (domList.indexOf(childNode.tagName) == -1) {
        if (childNode.innerText) {
          var spanNode = document.createElement('p');
          spanNode.textContent = childNode.innerText;
          childNode.parentNode.insertBefore(spanNode, childNode);
        }
        node.removeChild(childNode);
        i--;
      } else {
        var attributes = childNode.attributes;
        for (var j = 0; j < attributes.length; j++) {
          var attr = attributes[j];
          if (attr.name !== 'style' && attr.name !== 'class' && attr.name !== 'color' && attr.name !== 'face') {
            childNode.removeAttribute(attr.name);
            j--;
          }
        }
        removeOtherTags(childNode);
      }
    }
  }
}
function filterHTMLTags(htmlString) {
  return htmlString.replace(/<[^>]*>?/gm, '');
}
function formatHTMLFunc(htmlString) {
  try {
    var parser = new DOMParser();
    var doc = parser.parseFromString(htmlString, 'text/html').body;
    removeOtherTags(doc);
    return doc.innerHTML;
  } catch (err) {
    return filterHTMLTags(htmlString);
  }
}