Re: ajax request with no response

From	Stefan Weiss <krewecherl@gmail.com>
Newsgroups	comp.lang.javascript
Subject	Re: ajax request with no response
Date	2012-12-10 00:53 +0100
Organization	albasani.net
Message-ID	<ka3895$a7g$1@news.albasani.net> (permalink)
References	<67WdnSfJBNQHTV7NnZ2dnUVZ_uGdnZ2d@westnet.com.au> <7171452.m6WORY6t7m@PointedEars.de> <0pudneAzZbF8YlnNnZ2dnUVZ_h-dnZ2d@westnet.com.au>

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On 2012-12-09 22:17, Andrew Poulos wrote:
> On 10/12/2012 5:51 AM, Thomas 'PointedEars' Lahn wrote:
>> There is always a response.  As much too often with your questions, why do
>> you not try it *before* you post?
>>
>> <http://www.catb.org/~esr/faqs/smart-questions.html#idp29963616>
> 
> 1. You knew that "There is always a response." I did not. Nothing I've 
> read about ajax stated that. Still I do not fully understand what "There 
> is always a response." means.

There isn't necessarily always a response from the XMLHttpRequest
target, but the XHR object will still (eventually) reach a readyState of 4.

This holds true even if

- the provided URL is not valid
- the URL could not be loaded (DNS failure, server down, ...)
- the connection breaks down before the response
- the remote server is shut down before it can send the response
- the remote server redirects to another URL
- the client calls the XHR's abort() method
- the client navigates away before receiving a response
- the XHR.timeout value was reached
- etc.

In theory, unless you set a timeout for the XHR (where supported), it
could take forever before you get to the readyState=4 stage, because TCP
connections don't have a maximum duration. In practice, I'd like to see
the system that can keep up a TCP connection forever. My personal record
was 2 months :)

- stefan

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Thread

ajax request with no response Andrew Poulos <ap_prog@hotmail.com> - 2012-12-09 10:43 +1100
  Re: ajax request with no response Stefan Weiss <krewecherl@gmail.com> - 2012-12-09 01:17 +0100
    Re: ajax request with no response JJ <jaejunks@glegooilma-swapit.com> - 2012-12-10 04:17 +0000
      Re: ajax request with no response Stefan Weiss <krewecherl@gmail.com> - 2012-12-10 11:03 +0100
        Re: ajax request with no response JJ <jaejunks@glegooilma-swapit.com> - 2012-12-11 11:06 +0000
  Re: ajax request with no response Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-12-09 19:51 +0100
    Re: ajax request with no response Andrew Poulos <ap_prog@hotmail.com> - 2012-12-10 08:17 +1100
      Re: ajax request with no response Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-12-10 00:25 +0100
      Re: ajax request with no response Stefan Weiss <krewecherl@gmail.com> - 2012-12-10 00:53 +0100

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