AJAX isn't working

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AJAX isn't working

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The-Phantom
New Member

Posts: 10
Joined: Aug 2010

O.P. AJAX isn't working

Sometimes, when I do an AJAX request, it just stays at the readyState of 1, thereby hanging WLM. Sometimes, however, it doesn't happen. I can still access the page by browsing to it via a browser, so it's not a network problem. What's happening?

This post was edited on 08-28-2010 at 01:33 PM by The-Phantom.

08-28-2010 01:33 PM

V@no
Full Member

sexy

Posts: 162
Joined: Mar 2004

RE: AJAX isn't working

I think there would be much better chance get a good answer if you'd post the AJAX code you are using...

08-29-2010 05:31 AM

The-Phantom
New Member

Posts: 10
Joined: Aug 2010

O.P. RE: AJAX isn't working

Okay. I've made a simple script to demonstrate it. Here's the only JS file:

var xhr;
var ready;
function OnEvent_ChatWndSendMessage(Wnd, Message)
{
if(Message.substr(0, 10) != "/ajax-test")
return "";
Debug.Trace("Retrieving " + Message.substr(11));
var Iter = 0;
xhr = new ActiveXObject("Microsoft.XMLHTTP");
xhr.open("GET", encodeURI(Message.substr(11)), true);
xhr.onreadystatechange = function()
{
if(xhr.readyState == 4)
ready = true;
};
ready = false;
xhr.send();
while(!ready)
// If I don't check for this here, it just hangs up because ready is always false and this becomes an infinite loop
if(Iter++ > 10000000)
{
Debug.Trace("Error.");
return "";
}
Debug.Trace(xhr.responseText);
return "";
}

With the appropriate ScriptInfo.xml, I've tested it with several URLs, and here are the results:

Function called: OnEvent_ChatWndSendMessage
Retrieving http://example.com/
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=utf-8">
<TITLE>Example Web Page</TITLE>
</HEAD>
<body>
<p>You have reached this web page by typing "example.com",
"example.net","example.org&quot
or "example.edu" into your web browser.</p>
<p>These domain names are reserved for use in documentation and are not available
for registration. See <a href="http://www.rfc-editor.org/rfc/rfc2606.txt">RFC
2606</a>, Section 3.</p>
</BODY>
</HTML>

Function called: OnEvent_ChatWndSendMessage
Retrieving http://www.example.com/
Error.
Function called: OnEvent_ChatWndSendMessage
Retrieving http://www.msgplus.net/
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
<meta name="norton-safeweb-site-verification"
...
</div>

</body>
</html>

Function called: OnEvent_ChatWndSendMessage
Retrieving http://www.google.com/
Error.

08-29-2010 07:09 AM

Matti
Elite Member

Script Developer and Helper

Posts: 1646
Reputation: 39
32 / Male

Joined: Apr 2004

RE: AJAX isn't working

Since you want to modify the sent message, you need to use a synchronous XMLHTTP request as opposed to an asynchronous request. You need to modify the return value of OnEvent_ChatWndSendMessage, so your script has to wait for the result before continuing execution.

This cannot and should not be done with an infinite loop!!! Your loop essentially blocks the entire Messenger thread, including the onreadystatechange callback!

js code:
function OnEvent_ChatWndSendMessage(Wnd, Message)
{
if(Message.substr(0, 10) != "/ajax-test")
return "";
Debug.Trace("Retrieving " + Message.substr(11));
var xhr = new ActiveXObject("Microsoft.XMLHTTP");
// Note the 3rd argument: async = false, thus send() returns immediately
xhr.open("GET", encodeURI(Message.substr(11)), false);
xhr.send();
if(xhr.status === 200) { // HTTP 200 OK
// Success!
Debug.Trace(xhr.responseText);
} else {
// Something went wrong...
Debug.Trace("Error.");
}
// Return empty message
return "";
}

Tip: wrap your code blocks in [code=js]...[/code] tags for beautiful JavaScript syntax highlighting!

Plus! Script Developer | Plus! Beta Tester | Creator of Countdown Live | Co-developer of Screenshot Sender 5

Found my post useful? Rate me!

08-29-2010 07:10 PM

The-Phantom
New Member

Posts: 10
Joined: Aug 2010

O.P. RE: AJAX isn't working

That works perfectly! Huge thanks! [Image: jumpy.gif]

08-29-2010 07:57 PM

CookieRevised
Elite Member

Posts: 15517
Reputation: 173
– / Male

Joined: Jul 2003
Status: Away

RE: AJAX isn't working

quote:
Originally posted by The-Phantom
That works perfectly! Huge thanks!

sorry, but what Matti posted should not be done unless you want to slow down Messenger...

--------------

quick note to Matti first:

Matti, shouldn't that be:

// Note the 3rd argument: async = false, thus send() does not return immediately

The whole point of a synchronous call is exactly that send() will not return immediatly; it will wait until the whole thing is retrieved and thus it will slow down, if not lock up, Messenger!

Only when you have an asynchronous call, the send will return immediatly (and hence the reason why he had to make (bad) use of that loop)....

--------------

So, I do very highly recommend using an asynchronous method though! And actually advise against using a synchronous (async=false) method like Matti suggested.

By using a synchronous you will always end up slowing down and even locking up Messenger in one way or the other.

So, the problem you had is not because of the asynchronous call, but because you did not properly used the return function. Do not return (or wait to return) some text in the OnEvent_ChatWndSendMessage itself! That is not the proper way of doing things.

What you should be doing is:

1) in OnEvent_ChatWndSendMessage:
a) make the asynchronous call and assign another function to the onreadystatechange property
b) return ""
2) And only inside that other function which got assigned to onreadystatechange (and thus NOT outside this function like you did before with that loop), you do what you want to do.

Also note: in case you want to send some text back to the chat window in response to the outcome of the http call, check if the chat window still exists (highly important), then check if you actually can send some text. After that send the text you want with SendMessage... But all this also requires some additional scripting including keeping track of chat window objects and the contacts within the chats! So you will need to create and maintain an array on the global scope of the script too. And chats with more than one person will make this rather complicated though.

js code:
function OnEvent_ChatWndSendMessage(ChatWnd, Message) {
if (Message.substr(0, 10) === "/ajax-test") {
Debug.Trace("Retrieving " + Message.substr(11));
var xhr = new ActiveXObject("Microsoft.XMLHTTP");
xhr.open("GET", encodeURI(Message.substr(11)), true);
xhr.onreadystatechange = function() {
if (xhr.readyState === 4) {
if (xhr.status === 200) {
Debug.Trace("html: " + xhr.responseText);
} else {
Debug.Trace("error: " + xhr.status);
}
}
}
xhr.send();
return ""
}
}

Although I suspect that you better assign the XMLHTTP object in the global scope though. Can't be bothered checking on how Plus! handles such stuff/objects when used asynchronously...

---------

Also:

quote:
Originally posted by The-Phantom

js code:
function OnEvent_ChatWndSendMessage(ChatWnd, Message) {
if (Message.substr(0, 10) != "/ajax-test") return "";
// your code for the command /ajax-test here
}

That is very wrong and you should never be doing this. You cripple the proper workings of command handling by that. You should be doing the opposite:

js code:
function OnEvent_ChatWndSendMessage(ChatWnd, Message) {
if (Message.substr(0, 10) === "/ajax-test") {
// your code for the command /ajax-test here
return "";
}
}

Note that there is no Return outside the IF statement.

This post was edited on 08-29-2010 at 09:00 PM by CookieRevised.

.-= A 'frrrrrrrituurrr' for Wacky =-.

08-29-2010 08:24 PM

Matti
Elite Member

Script Developer and Helper

Posts: 1646
Reputation: 39
32 / Male

Joined: Apr 2004

RE: AJAX isn't working

Crap, Cookie beat me again.

I knew it would be impossible to return a value from within an asynchronous onreadystatechange callback, so I went with a synchronous call, which is basically just another way to block Messenger. I must agree that it is much better to just return an empty string when the command is captured and send something whenever the request finishes (without using the return value to send a message). My solution isn't really a solution, your solution is far superior.

And yes, that command parsing is very bad, basically you're pushing all the other commands and scripts out of the way and only let your command through. Not good.

* Matti needs some coffee...

Plus! Script Developer | Plus! Beta Tester | Creator of Countdown Live | Co-developer of Screenshot Sender 5

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08-29-2010 08:43 PM

The-Phantom
New Member

Posts: 10
Joined: Aug 2010

O.P. RE: AJAX isn't working

Yeah, I know about that error of mine. But can't it be like this?

js code:
function OnEvent_ChatWndSendMessage(Wnd, Message)
{
if(Message.substr(0, 10) != "/ajax-test")
return Message;
// handling for /ajax-test
}

Also, I know that I can do the same with an asynchronous request and sending another message, but what about receiving messages, where I need to change the text I receive? There's no function to "receive" another command, as far as I am aware…

08-30-2010 06:48 AM

CookieRevised
Elite Member

Posts: 15517
Reputation: 173
– / Male

Joined: Jul 2003
Status: Away

RE: AJAX isn't working

quote:
Originally posted by The-Phantom
Yeah, I know about that error of mine. But can't it be like this?
js code:
function OnEvent_ChatWndSendMessage(Wnd, Message)
{
if(Message.substr(0, 10) != "/ajax-test")
return Message;
// handling for /ajax-test
}

No...
1) nothing will be executed after the return statement
2) when you return the same message, the command will be send to your contact too (as text).
3) in that code you check if the message is _not_ "/ajax-test", it should be the opposite. You should never ever do != or !== to check for a command!! Again, this will cripple the proper workings of command handling... Always do a positive test, never a negative, for this.

See the code in my previous post for the proper way.

quote:
Originally posted by The-Phantom
Also, I know that I can do the same with an asynchronous request and sending another message, but what about receiving messages, where I need to change the text I receive? There's no function to "receive" another command, as far as I am aware…

There are some things you need to know whenyou want to change recieved text.

Biggest thing is that you can never change recieved text to text which is longer than the original.

Second, text you receive also includes your own send messages.

See OnEvent_ChatWndReceiveMessage event.

All this is also explained in the Plus! Scripting documents.

This post was edited on 08-30-2010 at 08:35 AM by CookieRevised.

.-= A 'frrrrrrrituurrr' for Wacky =-.

08-30-2010 08:31 AM

The-Phantom
New Member

Posts: 10
Joined: Aug 2010

O.P. RE: RE: AJAX isn't working

quote:
Originally posted by CookieRevised
No...
1) nothing will be executed after a return statement
2) when you return the same message, the command will be send to your contact too (as text).
3) in that code you check if the message is _not_ "/ajax-test", it should the opposite.

See the code in my previous post for the proper way.

I still don't get it. If it is the command I need, the if clause is skipped and the handling is performed. If it is not, the message is not changed and handling isn't executed. That's exactly the behaviour needed, isn't it?

quote:
There are some things you need to know whenyou want to change recieved text.

Biggest thing is that you can never change recieved text to text which is longer than the original.

Second, text you receive also includes your own send messages.

See OnEvent_ChatWndReceiveMessage event.

All this is also explained in the Plus! Scripting documents.

Yes, yes, I know. How could I be able to make some scripts without reading that first?

08-30-2010 08:40 AM

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