JSFiddle - React, Tailwind, and code Playground

HTML

<b class="abc" style="background-color:red; ">Change <i>here</i>!!</b>

<b style="background-color:#FFA; ">NO CHANGES HERE</b>

CSS

h1 {color:blue; font-size:22pt}

JavaScript

function jsChangeElementType(element,newtype) {
  var new_element = document.createElement(newtype),
    old_attributes = element.attributes,
    new_attributes = new_element.attributes,
    child = element.firstChild;
  for (var i = 0, len = old_attributes.length; i < len; i++) {
    new_attributes.setNamedItem(old_attributes.item(i).cloneNode());
  }
  do {
    new_element.appendChild(child);
  } while (child = child.nextSibling);
  element.parentNode.replaceChild(new_element, element);
}  // func

(function($) {
    $.fn.changeElementType = function(newType) {
        jsChangeElementType(this[0],newType);
    }
})(jQuery);

$("b.abc").changeElementType("h1");