Question

function a (){
    var b = null;
    if(window.XMLHttpRequest) b = new XMLHttpRequest();
    else if(window.ActiveXObject) b = new ActiveXObject("Microsoft.XMLHTTP");
    if(!b) b = new ActiveXObject("msxml2.XMLHTTP");
    return b;
}
var b=a();
function c(){
    var u = "ajax3_php.php?w="+ parseInt(Math.random()*88888);
    b.onreadystatechange = function (){
        if(b.status == 200 && b.readyState == 4){
            document.getElementById("divid").innerHTML = b.responseText;
        }
    }
    b.open("get", u, true);
    b.send();
}

And on the target page “ajax3_php.php”:

<?php
echo "OK";
?>

And on “divid” id
<div id=”divid”>Test</div>

the error message is:

Message: Unspecified error.
Line: 20
Char: 3
Code: 0
URI: http://localhost/lat1/ajax/ajax3.php

The shocking part is, this is on line 20:

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

What is wrong with that?

FYI : firebug says nothing.

Answer 1

This code seemed to do the trick.

function a()
{
    var b = null;
    if(window.XMLHttpRequest)
    {
        b = new XMLHttpRequest();
    }else if(window.ActiveXObject)
    {
        b = new ActiveXObject("Microsoft.XMLHTTP");
    }
    if(!b)
    {
        b = new ActiveXObject("msxml2.XMLHTTP");
    }
    return b;
}
var b = a();
function c()
{
    var u = "ajax3_php.php?w="+ parseInt(Math.random()*88888, 10);
    b.open("get", u, true);
    b.onreadystatechange = function ()
    {
        if(b.readyState === 4)
        {
            if(b.status === 200)
            {
                if(b.responseText)
                {
                    document.getElementById("divid").innerHTML = b.responseText;
                }
            }   
        }
    };
    b.send();
}

c();

I don’t have a silver bullet answer as to why the error was popping up, but the call to b.status was throwing an error when the readyState wasn’t 4. However, that particular error was one I ran into recently (but a different error type) when sending an empty string via innerHTML to an element in IE 8 (I suspected your responseText was empty, causing the error).

I took the liberty of fixing that code for you (along with a few other touches). There are no errors in IE 7-8, Quirks or none.

I hope this helps you.

-Matt

EDIT: I stumbled upon this MSDN post. It’s curious to see that their example code uses nested if blocks just like I did, yet no explanation. I’ll investigate further.

Link: http://msdn.microsoft.com/en-us/library/dd576252%28v=vs.85%29.aspx