IE6 specific Object Doesn't Support ... Error

[henryrhenryr]

Hi All

I'm using AJAX in an analytics script. All works nicely in Firefox and the script loads my php script which records some information in the database.

The part with the error in IE is the part which adds the events to the anchor elements. The error message from IE is:

Line 335: Object doesn't support this property or method.

The javascript line this refers to (I have confirmed this 100% even though line ref is wrong) is as follows:

links = document.getElementsByTagName('a');
 

As you can imagine I've tried looking for standard IE bugs for this type of line but nothing comes up.

Some thoughts I've had: it could be using "links" to name a variable (is links reserved)? It could be that "a" has to be "A". I have tried different combinations of these but no luck.

Hopefully someone can point me in the right direction!

Thanks in advance!

Henry

[acoder]

That line shouldn't cause errors. Can you post the rest of your code?

[henryrhenryr]

Hi

Thanks for helping out. I thought that might be the case. The relevant code is below. Hopefully it yields some answers...

/-------------------ANALYTICS--------------------------//
var xmlHttp; //ajax object
var vapk; //the visitor pk which is retrieved on entry and used on exit to update
var listeners = []; //array
 
function listenAllLinks() {
  if (!document.getElementsByTagName) return false;
  // find links in document
  aLinks = document.getElementsByTagName('a');
 
  // if link does have a id add one
  for (var i = 0; i < aLinks.length; i++) {
    addEvent( aLinks[i], 'click', exit, false );
    addEvent( aLinks[i], 'keypress', linkKeyPress, false );
  }
 
  // find buttons in document
  inputs = document.getElementsByTagName('input');
  for (var i = 0; i < inputs.length; i++) {
    type = inputs[i].getAttribute('type');
    // only attach events to buttons
    if ( type == 'submit' || type == 'button' ) {
      addEvent( inputs[i], 'click', exit, false );
      addEvent( inputs[i], 'keypress', linkKeyPress, false );
    }
  }
}
 
function linkKeyPress(e) {
  // check for return key press
  var keyID = (window.event) ? event.keyCode : e.keyCode;
  if (keyID == 13) {
    exit(e);
  }
}
 
function addEvent( thisE, evType, fn, useCapture ) {
  // Updated version which captures passed events
  if (thisE.AddEventListener) {
    thisE.AddEventListener(evType, fn, useCapture);
    return true;
  }
  else if (thisE.attachEvent) {
    var r = thisE.attachEvent('on' + evType, fn);
    window.listeners[window.listeners.length] = [ thisE, evType, fn ];
    return r;
  }
  else {
    var xEventFn = thisE['on' + evType];
    if (typeof thisE['on' + evType] != 'function')    {
      thisE['on' + evType] = fn;
    }
    else {
      thisE['on' + evType] = function(e) { xEventFn(e); fn(e); };
    }
  }
}
 
function findSourceElement(e) {
  // finds event source
  if (typeof e == 'undefined') {
    var e = window.event;
  }
 
  var source;
  if (typeof e.target != 'undefined') {
    source = e.target;
  }
  else if (typeof e.srcElement != 'undefined') {
    source = e.srcElement;
  }
  else {
    return true;
  }
  if (source.nodeType == 3) {
    source = source.parentNode;
  }
  return source;
}
 
function getFormTarget( elt ) {
  // returns the form action attribute from
  // if given the child node of that form
  target = null;
  parentElt = elt.parentNode;
  if( parentElt.nodeType == 1 ) {
    if( parentElt.tagName == 'FORM' ) {
      target = parentElt.getAttribute('action');
    }
    else {
      target = getFormTarget( elt.parentNode );
    }
  }
  else {
    target = getFormTarget( elt.parentNode );
  }
  return target;
}
 
function exit(e) {
  // records click information using ajax
  source = findSourceElement(e);
  tag = source.tagName;
  var id,label,target
 
  if( tag == 'IMG') {
    if( source.parentNode.tagName == 'A' ) {
      target = source.parentNode.href;
    }
  }
 
  if( tag == 'A' ) {
    target = source.href;
  }
 
  if( tag == 'INPUT' ) {
    return true;
    if( source.getAttribute('type') == 'submit' ) {
      target = getFormTarget( source );
    }
    else {
      target = 'script';
    }
  }
 
  if (window.vapk) {
    xmlHttp=GetXmlHttpObject();
    if (xmlHttp==null) {
      //alert ("Browser does not support HTTP Request")
      return true;
    }
 
    var script= "ajax/analytics_exit.php";
    target = escape( target );
    var url=script+"?vapk="+window.vapk+"&exit_page="+target+"&rand="+Math.random();
 
    xmlHttp.onreadystatechange=stateChanged;
    xmlHttp.open("GET",url,true);
    xmlHttp.send(null);
  }
  return true;
}
 
function entry(ref,uri) {
  //alert("entry running now");
  xmlHttp=GetXmlHttpObject();
  if (xmlHttp==null) {
    //alert ("Browser does not support HTTP Request")
    return
  }
 
  var sid= "<?php echo (isset($_COOKIE['PHPSESSID'])) ? $_COOKIE['PHPSESSID'] : NULL; ?>";
  var cid= "<?php echo (isset($_SESSION['cid'])) ? $_SESSION['cid'] : 0; ?>";
  var ip= "<?php echo $_SERVER['REMOTE_ADDR']; ?>";
  var res= screen.width + "x" + screen.height;
  var agent= "<?php echo $_SERVER['HTTP_USER_AGENT']; ?>";
  if (ref==undefined) {
    ref = 'direct';
  }
  if (uri==undefined) {
    uri = 'unknown';
  }
 
  var script= "ajax/analytics_entry.php";
 
  var url=script+"?cid="+cid+"&ip="+ip+"&res="+res+"&agent="+agent+"&ref="+ref+"&uri="+uri+"&sid="+sid;
 
  xmlHttp.onreadystatechange=stateChanged;
  xmlHttp.open("GET",url,true);
  xmlHttp.send(null);
}
 
function stateChanged() {
  if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete") {
    var r=xmlHttp.responseText;
    if (!isNaN(r)) {
      window.vapk=r;
      return;
    }
    else if (r.indexOf('http://')==0) {
      window.location=r;
    }
    else {
      return;
    }
  }
}
 
function GetXmlHttpObject() {
  var xmlHttp=null;
  try { // Firefox, Opera 8.0+, Safari
    xmlHttp=new XMLHttpRequest();
  }
  catch (e) { //Internet Explorer
    try { xmlHttp=new ActiveXObject("Msxml2.XMLHTTP"); }
    catch (e) { xmlHttp=new ActiveXObject("Microsoft.XMLHTTP"); }
  }
  return xmlHttp;
}
 
//------------end analytics------------//
 

Thanks again!

[acoder]

Can you also post the corresponding HTML?

[henryrhenryr]

Hi acoder

There isn't really any corresponding HTML as such but here is all the information I can think relates to the analytics functions.

The javascript is loaded by the following:

<body onload="load()">
 

//external
function load() {
  listenAllLinks();
}
 

The pages contain hundreds of links all in standard format: <a href="..." title="...">...</a>.

The idea is that the listenAllLinks() function adds events to all the anchor elements. When somone clicks on the anchor element, the database is updated with the click recorded.

I call the entry() function on page load (on an inline script) to record the visit after the page has loaded.

Hope that gives all the information. I'm a little mystified by the problem, hence asking for help!

Thanks again!

Henry

[acoder]

So this happens when adding the events, right?

Check your form ids that they're not reserved words, etc.

[henryrhenryr]

after changing

links= document.getElementsByTagName('a');
 

to

aLinks= document.getElementsByTagName('a');
 

the script now works! I don't believe it - this bug has been causing me headaches for months.

Simple is normally the explanation. Thanks for your help acoder!

Henry

[acoder]

Glad you got it working.

Check your code for elements named "links". IE 6 is easily confused!