AJAX questions (not completely new, but don't know all the features)

[kratsg]

Ok, I'm kinda confused on how to word this question, but let's say I've got a chatroom for instance.

 

So we post a message, uses ajax to submit the info to the php file that adds the information to the database. If the message has some error, how can I get the php file to send back a javascript alert (like

window.alert('Sorry, this message had an error. Please try again later.');

so that it would automatically pop-up in the user window?

 

Similarly, if someone posts a new message to the database, how can I automatically create an AJAX call to a php file to update the chat room messages to include the new message?

 

Right now, my solution for the latter is to auto-call the php file every 3 seconds and simply grab all the messages (up to a certain point) and re-update the chatroom messages, whether there's a new message or not.

[BlueSkyIS]

define a javascript function to be used as the connection object's onreadystatechange, for instance:

 

function sndItemReq3(action) {
var http4 = createRequestObject();
http4.open("get", action);
http4.onreadystatechange = function() {
	if (http4.readyState == 4) { // This is the response from the server
		var serverResponse = http4.responseText;

                 if (serverReponse == "error") {
		      window.alert('Sorry, this message had an error. Please try again later.');
                 }
	}

}
http4.send(null);
return 1;
}

 

This function defines the connection object and then defines onreadystatechange as a function. Whenever the connection object performs an action, it changes it's ready state, hence our ability to define what it does onreadystatechange. onreadystatechange == 4 is when we get the response from the server script, typically a string.

[kratsg]

define a javascript function to be used as the connection object's onreadystatechange, for instance:

 

function sndItemReq3(action) {
var http4 = createRequestObject();
http4.open("get", action);
http4.onreadystatechange = function() {
	if (http4.readyState == 4) { // This is the response from the server
		var serverResponse = http4.responseText;

                 if (serverReponse == "error") {
		      window.alert('Sorry, this message had an error. Please try again later.');
                 }
	}

}
http4.send(null);
return 1;
}

 

This function defines the connection object and then defines onreadystatechange as a function. Whenever the connection object performs an action, it changes it's ready state, hence our ability to define what it does onreadystatechange. onreadystatechange == 4 is when we get the response from the server script, typically a string.

 

Ok, I understand my first problem and that makes sense. Now, what if I wanted to change the user's php session values? Would I be able to do that through AJAX or would I have to send the user to a new page?

 

And what about my second question? Any ideas?

[kratsg]

BUMP (sorry, nobody's answered second question yet)