AJAX: How do you return different states?

jtown

When I use JS/Ajax to call a php script the php can only echo text to the handle. Javascript then displays this stream in the proper place. How do I send back different error status? Do I just have to echo "Error" then in JS do a if(var == "Error") display something different?

I'm new to Ajax and was wondering if there's a better way.

Thanks!

NogDog

You might be able to do something with returning a HTTP header, such as a "404 Not Found", etc., then do a check in your AJAX handler JavaScript:

if ( request.readyState == 4 ){  // 4 is "complete" 
  if ( request.status == 200 ){
    // HTTP OK, carry out your normal Ajax processing
    // ... 
  }else{
    // something went wrong, report the error
    error( "HTTP "+request.status+".  An error was »
             encountered: "+ request.statusText );
  }
}

I have not tested this, though, so I'm not sure how well it does or does not work.

If you are actually using the "X" part of "AJAX" and returning valid XML data, then it should be a fairly simple matter to include a "status" element or attribute in that data, and have your JavaScript check that value to decide whether or not an error occurred.

jtown

Ah I see. I guess I'm sort of doing it the same way ... return status and check in JS basically. I was just wondering if I'm missing something fundamental.

NogDog

jtown wrote:
Ah I see. I guess I'm sort of doing it the same way ... return status and check in JS basically. I was just wondering if I'm missing something fundamental.

If you are, I'm missing it, too, and would be very interested in knowing about it. 🙂 (I'm still fairly new to the AJAX world and by no means claim to know all there is to know about it.)

Weedpacket

Using the HTTP response code is the appropriate mechanism for reporting error conditions; RFC2616 lists the recognised response codes (basically, 50 for server faults and 40 for client errors).