Displaying Errors on Ajax return function.

[Gregg Bolinger]

Maybe I am doing something wrong, but...

Let's say I have the following (psuedo code)

function handleStateChange() 
{
   if(xmlHttp.readyState == 4) 
   {
      if (xmlHttp.status == 200)
      {
           someCallBackFunction(xmlHttp.responseXML);
      }
    }
}
 
function someCallBackFunction(res)
{
    //an error occurs here
}

In someCallBackFunction, if there is a javascript error, the browser never reports it. Very hard to debug. I've tried overriding the window.onerror but I don't believe that is even being thrown. So how would I go about dealing with this?

Thanks.

[Eric Pascarello]

How do you know an error occurs if it is not being reported? That is the answer I want to know. lol

Eric

[Gregg Bolinger]

Because the page just stops. I can put alert messages in the function and move them until they don't display. Then I kind of know where the error is. For example:

function someCallBackFunction(res)
{
   alert("Made it");
   var a = 0;
   alert("a: " + a);
   var b = a + c;
   alert("b: " + b); // This line doesn't get called because c is not an object.
}

The last alert never happens. But the browser doesn't report the problem with the variable c.
[ May 02, 2006: Message edited by: Gregg Bolinger ]

[Eric Pascarello]

With all of my fucntion I use try catch statements which are logged to my server. Here is a basic exacmple that shows you basic functionality with try catch

function someCallBackFunction(res){
  try{
   alert("Made it");
   var a = 0;
   alert("a: " + a);
   var b = a + c;
   alert("b: " + b); // This line doesn't get called because c is not an object.
  }
  catch(e){
    alert("Error in someCallBackFunction:\n\nName: " + e.name + "\nDesc: " + e.description + "\nMsg: " + e.msg); 
  }
}

See if that catches it.

Eric

[Gregg Bolinger]

That worked! Thanks Eric.

[Gregg Bolinger]

Ok, so I have e.message, e.description, e.name... I am trying to find the other methods available, if any. Google hasn't turned up anything yet. Anyone know where I would find these defined?

[Eric Pascarello]

that is all you are going to get.

Loop through the properties of e to see it by using for in

Eric