[Greasemonkey] Bug in GM_xmlhttpRequest?

[Jeremy Dunck]

On 5/4/05, Mark Pilgrim <pilgrim at gmail.com> wrote:
> I'm calling GM_xmlhttpRequest and my onload callback function is
> getting called twice.  Is this expected behavior?

No.  It is possible that I'm not seeing what you're seeing, because
I'm running a version that has a patch against GM_xmlhttpRequest;
however, I expect that that patch only affected onreadystateload.

That said...

> code snippet:

I changed to this:


GM_xmlhttpRequest({                                                  
   method: 'GET',                                                    
   url: 'http://greaseblog.blogspot.com/atom.xml',                   
   headers: {                                                        
       'User-agent': 'Mozilla/4.0 (compatible) Greasemonkey',        
       'Accept': 'application/atom+xml,application/xml,text/xml',    
   },                                                                
   onload: function(responseDetails) {                               
GM_log('in onload');
       var parser = new DOMParser();                                 
       var dom = parser.parseFromString(responseDetails.responseText,
           "application/xml");                                       
//exporting for shell debugging.
window.xmldom = dom;
       var entries = dom.getElementsByTagName('entry');              
GM_log('got entries:' + entries.length);       	
       var title, p;                                                 
       for (var i in entries) {                                      
GM_log('entry[' + i + ']');       	
           title = entries[i].getElementsByTagName('title')[0];      
GM_log('got title');       	
           p = document.createElement('p');                          
           p.appendChild(document.createTextNode(title.textContent));
GM_log('added title textcontent');       	
           document.body.appendChild(p);                             
GM_log('added container p');       	           
       }                                                             
   }                                                                 
});                                                                  

====
Note that in the loop, you'll get 
entry[0]
entry[1]
and so on.
But at the end, you'll die on:
entry[length].

The problem is that while, for native JS arrays, the length property
is not included in enumeration, it apparently is included on
HTMLCollection (which is what I got when running your sample code).

I think this could be considered a bug in Firefox, but I'm not certain.

So: to do what you want, you'll have to use crusty old for(i=0;
i<entries.length; i++).

Now, if that doesn't address the "calling two times" problem, please
let me know.