<script>  
function includeHTML() {  
  var z, i, elmnt, file, xhttp;  
  /* Loop through a collection of all HTML elements: */  
  z = document.getElementsByTagName("*");  
  for (i = 0; i < z.length; i++) {  
    elmnt = z[i];  
    /*search for elements with a certain atrribute:*/  
    file = elmnt.getAttribute("HERE-include-html");  
    if (file) {  
      /* Make an HTTP request using the attribute value as the file name: */  
      xhttp = new XMLHttpRequest();  
      xhttp.onreadystatechange = function() {  
        if (this.readyState == 4) {  
          if (this.status == 200) {elmnt.innerHTML = this.responseText;}  
          if (this.status == 404) {elmnt.innerHTML = "Page not found.";}  
          /* Remove the attribute, and call this function once more: */  
          elmnt.removeAttribute("HERE-include-html");  
          includeHTML();  
        }  
      }  
      xhttp.open("GET", file, true);  
      xhttp.send();  
      /* Exit the function: */  
      return;  
    }  
  }  
}  
</script>

<script>  
includeHTML();  
</script>