JSFiddle - React, Tailwind, and code Playground

HTML

<div id="user_list"></div>
<script type="text/javascript">
    startUp();
</script>

JavaScript

var asyncRequest = function() {
  function handleReadyState(o, callback) {
    if (o && o.readyState == 4 && o.status == 200) {
        {
        callback(o);
      }
    }
  }

  var getXHR = function() {
    var http;
    try {
      http = new XMLHttpRequest;
        getXHR = function() {
          return new XMLHttpRequest;
        };
    }
    catch(e) {
      var msxml = [
        'MSXML2.XMLHTTP.3.0', 
        'MSXML2.XMLHTTP', 
        'Microsoft.XMLHTTP'
      ];

      for (var i=0, len = msxml.length; i < len; ++i) {
        try {
          http = new ActiveXObject(msxml[i]);
          getXHR = function() {
            return new ActiveXObject(msxml[i]);
          };

          break;
        }

        catch(e) {}
      }
    }

    return http;

  };

  return function(method, uri, callback, postData) {
    var http = getXHR();
      http.onreadystatechange = function(){handleReadyState(http, callback)};
    http.open(method, uri, true);
    http.send(postData || null);

    return http;
  };

}();

function gotUsers(o)
{
    document.getElementById("user_list").innerHTML=o.responseText;
}

function startUp() {
    asyncRequest('POST', '/echo/html/', 
                  gotUsers, 
                 "html=<p>user1</p><p>user2</p><p>user3</p>" );
    
}