function createRequestObject() {
  var ro;
  var browser = navigator.appName;
  if(browser == "Microsoft Internet Explorer"){
    ro = new ActiveXObject("Microsoft.XMLHTTP");
  }else{
    ro = new XMLHttpRequest();
  }
  return ro;
}

var http = createRequestObject();

function getDynamicChapter(book_id, chapter_number, total_chapters) {
  http.open('get', '/php/getChapter.php?book_id='+book_id+'&chapter='+chapter_number+'&total='+total_chapters);
  http.onreadystatechange = showDynamicChapter;
  http.send(null);
}

function showDynamicChapter() {
  if(http.readyState == 4){
    document.getElementById('dynamic').innerHTML = http.responseText;
  }
}