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Re: XHR: Passing Parameters to a ready-state-change Function

Message-ID <1847393.YeQSDktdzs@PointedEars.de> (permalink)
From Thomas 'PointedEars' Lahn <PointedEars@web.de>
Organization PointedEars Software (PES)
Date 2012-09-06 21:49 +0200
Subject Re: XHR: Passing Parameters to a ready-state-change Function
Newsgroups comp.lang.javascript
References <09ef48tfsgucbl7m49ggao3be5r0kb7v13@4ax.com> <k2akj4$bca$1@news.albasani.net> <10463793.jXXL31m3yW@PointedEars.de>
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Thomas 'PointedEars' Lahn wrote:

> Stefan Weiss wrote:
>> […]
>>   function fetch (url, callback) {
>>       // (minimal example)
>>       var xhr = new XMLHttpRequest();
>>       xhr.open("GET", url, true);
>>       xhr.onreadystatechange = function () {
>>           if (xhr.readyState == "4") {
>>               callback(xhr.responseText);
>>           }
>>       };
>>       xhr.send();
>>   }
>> […]
>> 
>> What am I missing?
> 
> At first glance, that the `readyState' property values are of type Number,
> and that xhr.send(null) should be called with GET.

At second glance, that readyState == 4 does not need to mean success (you 
have to check the `status' as well) and that `callback' has no idea whether 
an empty `responseText' means success or failure.  I think that should be 
fixed even in a minimal XHR example:

  function fetch (url, callback)
  {
    /* (minimal example) */
    var xhr = new XMLHttpRequest();
    xhr.open("GET", url, true);
    xhr.onreadystatechange = function () {
      if (xhr.readyState == 4 && xhr.status == 200)
      {
        callback(xhr.responseText);
      }
    };
    xhr.send(null);
  }

BTW, it is acceptable to see that you also use the space-before-parameter-
list convention.  It makes calls so much easier to find, does it not?


PointedEars
-- 
var bugRiddenCrashPronePieceOfJunk = (
    navigator.userAgent.indexOf('MSIE 5') != -1
    && navigator.userAgent.indexOf('Mac') != -1
)  // Plone, register_function.js:16

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XHR: Passing Parameters to a ready-state-change Function Gene Wirchenko <genew@ocis.net> - 2012-09-05 13:53 -0700
  Re: XHR: Passing Parameters to a ready-state-change Function Jim T. <x@y.z> - 2012-09-05 17:46 -0400
    Re: XHR: Passing Parameters to a ready-state-change Function Gene Wirchenko <genew@ocis.net> - 2012-09-05 17:30 -0700
      Re: XHR: Passing Parameters to a ready-state-change Function Jim T. <x@y.z> - 2012-09-05 20:55 -0400
  Re: XHR: Passing Parameters to a ready-state-change Function Jim T. <x@y.z> - 2012-09-05 21:43 -0400
    Re: XHR: Passing Parameters to a ready-state-change Function Jim T. <x@y.z> - 2012-09-05 21:49 -0400
  Re: XHR: Passing Parameters to a ready-state-change Function Stefan Weiss <krewecherl@gmail.com> - 2012-09-06 18:56 +0200
    Re: XHR: Passing Parameters to a ready-state-change Function Gene Wirchenko <genew@ocis.net> - 2012-09-06 10:55 -0700
    Re: XHR: Passing Parameters to a ready-state-change Function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-06 21:38 +0200
      Re: XHR: Passing Parameters to a ready-state-change Function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-06 21:49 +0200
    Re: XHR: Passing Parameters to a ready-state-change Function Gene Wirchenko <genew@ocis.net> - 2012-09-06 15:49 -0700
      Re: XHR: Passing Parameters to a ready-state-change Function Tim Streater <timstreater@greenbee.net> - 2012-09-07 09:15 +0100
        Re: XHR: Passing Parameters to a ready-state-change Function Gene Wirchenko <genew@ocis.net> - 2012-09-07 09:58 -0700
          Re: XHR: Passing Parameters to a ready-state-change Function Tim Streater <timstreater@greenbee.net> - 2012-09-07 19:14 +0100
            Re: XHR: Passing Parameters to a ready-state-change Function cezary.tomczyk@gmail.com - 2012-09-07 13:51 -0700
              Re: XHR: Passing Parameters to a ready-state-change Function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-08 00:52 +0200
                Re: XHR: Passing Parameters to a ready-state-change Function cezary.tomczyk@gmail.com - 2012-09-07 16:32 -0700
                Re: XHR: Passing Parameters to a ready-state-change Function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-08 09:48 +0200
                Re: XHR: Passing Parameters to a ready-state-change Function Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2012-09-08 02:09 -0700
                Re: XHR: Passing Parameters to a ready-state-change Function Tim Streater <timstreater@greenbee.net> - 2012-09-08 11:09 +0100
                Re: XHR: Passing Parameters to a ready-state-change Function Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2012-09-08 03:39 -0700
                Re: XHR: Passing Parameters to a ready-state-change Function John G Harris <john@nospam.demon.co.uk> - 2012-09-08 15:00 +0100
            Re: XHR: Passing Parameters to a ready-state-change Function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-07 23:44 +0200
              Re: XHR: Passing Parameters to a ready-state-change Function Tim Streater <timstreater@greenbee.net> - 2012-09-07 23:08 +0100
                Re: XHR: Passing Parameters to a ready-state-change Function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-08 00:46 +0200
                Re: XHR: Passing Parameters to a ready-state-change Function Tim Streater <timstreater@greenbee.net> - 2012-09-08 11:11 +0100
                Re: XHR: Passing Parameters to a ready-state-change Function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-08 14:21 +0200
                Re: XHR: Passing Parameters to a ready-state-change Function Tim Streater <timstreater@greenbee.net> - 2012-09-08 17:06 +0100
                Re: XHR: Passing Parameters to a ready-state-change Function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-08 20:41 +0200
                Re: XHR: Passing Parameters to a ready-state-change Function Dr J R Stockton <reply1236@merlyn.demon.co.uk.invalid> - 2012-09-09 20:04 +0100
            Re: XHR: Passing Parameters to a ready-state-change Function Gene Wirchenko <genew@ocis.net> - 2012-09-09 18:40 -0700
              Re: XHR: Passing Parameters to a ready-state-change Function "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2012-09-10 07:21 +0000
              Re: XHR: Passing Parameters to a ready-state-change Function Tim Streater <timstreater@greenbee.net> - 2012-09-10 09:03 +0100
                Re: XHR: Passing Parameters to a ready-state-change Function "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2012-09-10 13:59 +0000
                Re: XHR: Passing Parameters to a ready-state-change Function Tim Streater <timstreater@greenbee.net> - 2012-09-10 15:35 +0100
                Re: XHR: Passing Parameters to a ready-state-change Function "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2012-09-10 22:42 +0000
                Re: XHR: Passing Parameters to a ready-state-change Function Scott Sauyet <scott.sauyet@gmail.com> - 2012-09-11 10:09 -0700
                Re: XHR: Passing Parameters to a ready-state-change Function Tim Streater <timstreater@greenbee.net> - 2012-09-11 22:42 +0100

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