BB5 - Fix for jQuery.ajax "no transport" error

[adambiggs]

After spending half a day trying to figure out why I was getting "no transport" errors from all my ajax calls in BB5, an obscure google search led me to this little gem:

// force cross-site scripting (as of jQuery 1.5)
jQuery.support.cors = true;

Maybe this should be added somewhere in jQM? Either way thought this might save others from wasting a few hours like I did :)

[jblas]

@adambiggs

Do you have an URL to the article that discusses that little gem and why it's necessary? Are you using jQuery Mobile in a PhoneGap application?

[adambiggs]

Here's the post where I found it (not jQM related):

http://blueonionsoftware.com/blog.aspx?p=03aff202-4198-4606-b9d6-686fd13697ee

Yes I'm using this for a PhoneGap application, but I believe I was also having this problem when the code was hosted on the server.

[vikaskanani]

When I started with BB5, I also found that article and that worked at that time.
By default it is true in jquery 1.6.1, so we should check it whether it really requires or not.

[vikaskanani]

Figured out, jQuery.support.cors value depends xhr and it depends on browser. so that's true, we should add it in js.

[toddparker]

I wonder if there are downsides to adding this to our code by default. Anyone know the details of how this works?

[nawar]

I have to mention that I had the same issue, but thanks to @vikaskanani, who pointed me to this page, I was able to resolve it for the BB5 version of my app. I was using jQuery v1.6.2 and the Jul 29th nightly build of JQM at the time of compilation. I think it would be nice to fix this so others won't waste time with the same issue.

[toddparker]

Anyone able to say what the impact of adding this will be? Not too sure we want to use this without understanding the impact.

[nawar]

Looking at jQuery docs, it tells that the

 jQuery.support.cors 

property can be enabled individually for the working environment which allows cross-domain XHR requests but do not support the cors property above; here, I assume the environment is the BB5 MIDP-based browser. It would be nice to enable this property upon browser detection:

 var UA = navigator.userAgent;
 if (UA.indexOf("BlackBerry") >= 0)  {      
     if (UA.indexOf("MIDP") >= 0)  {
     $.support.cors = true;
     }
 }      

[vikaskanani]

There will be no impact on jQuery Mobile framework. I read this technical report on cors. It says that to protect the data, we should not allow to access data from other origin.

Should we include this in our library?
I was using PhoneGap for BlackBerry app, with jQuery Mobile. All HTML pages resides in phone, and can be access as local:///index.html. So when I call ajax to my server to sync data, origin will be different than local. So I must need to override the default setting of BlackBerry OS 5.0 browsers. There no major reason that we should add it into our library. Users who face this issue can find out this solution like nawar did.

Also one more important point. When we call ajax from our pc's browser, with local file like:
file:///D:/index.html, then we may not use ajax to fetch data from other origin. This is default behavior of most of the browser. I think we cannot override cors settings in this case. That will be enough to know that we should change settings or not.

My final suggestion is not to include it.

[toddparker]

Closing as won't fix.

[lexdabest]

Well for me, using $.support.cors = true; help solved hours of wasted time. Thanks jasondscott