http request javascript

<script>
function loadDoc() {
  var xhttp = new XMLHttpRequest();
  
  //looking for a change or state , like a request or get.
  xhttp.onreadystatechange = function() {
     
     //if equal to 4 means that its ready.
    // if equal to 200 indicates that the request has succeeded.
    if (this.readyState == 4 && this.status == 200) {
      document.getElementById("demo").innerHTML = this.responseText;
    }
  };
  
  //GET method for gettin the data // the file you are requesting
  xhttp.open("GET", "TheFileYouWant.html", true);
  
  //sending the request
  xhttp.send();
}function httpGetAsync(url, callback) {
  var xmlHttp = new XMLHttpRequest();
  xmlHttp.onreadystatechange = function() { 
    if (xmlHttp.readyState == 4 && xmlHttp.status == 200)
      callback(xmlHttp.responseText);
  }
  xmlHttp.open("GET", url, true); // true for asynchronous 
  xmlHttp.send(null);
}var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {

    if (this.readyState == 4 && this.status == 200) {

        // Typical action to be performed when the document is ready:
       
 document.getElementById("demo").innerHTML = xhttp.responseText;

    }
};

xhttp.open("GET", "filename", true);

xhttp.send();