Invoking contents() on a jQuery constructed iframe causes javascript error

[ts@…]

• The version affected

jquery-1.7.1.js

• The browsers you are able to reproduce the bug in

Google Chrome 16.0.912.77 Firefox 7.0.1

• The operating system you experienced the bug on

Debian Squeeze

• Step-by-step instructions on how to reproduce the issue

Execute the following code, for example in the Chrome console (in a page with jQuery loaded): $("<iframe src=' http://example.com'></iframe>").contents();

• What you expect to happen, and what actually happens

I expect the expression above to execute without generating a javascript error. What happens is that a javascript error is logged in the console. This occurs for both Firfox and Chrome.

Example of Chrome error message:

Uncaught TypeError: Cannot read property 'document' of null jQuery.each.contentsjquery-1.7.1.js:5515 jQuery.extend.mapjquery-1.7.1.js:771 jQuery.each.jQuery.fn.(anonymous function)jquery-1.7.1.js:5520 (anonymous function)

• Information on other browsers where the issue does not occur

Only tested in Chrome and Firefox

[sindresorhus]

The iframe needs to be inserted into the body and loaded before you can get it's contents.

Something like this:  http://jsfiddle.net/mofle/M3pHT/

Also make sure it's on the same domain and subdomain.

In the future we would appreciate if you provided a testcase on jsfiddle when reporting bugs.

[ts@…]

I am aware that this only happens if the iframe is not inserted into the body. However, I thought this is an obvious and easy to correct bug in the jQuery code, so I thought I would report it, since javascript errors are always embarrassing.

I actually did make a test case on jsfiddle, but the ticket tracker would not let me submit the bugreport, always telling me that it is spam, until I figured that it may be caused by the short jsfiddle URL and removed it. Even after I created the ticket, the issue tracker would not let me add the jsfiddle URL as a comment. However is in charge of the Issue Tracke may want to have a look at this :-).

[anonymous]

By the way, this is not something I invented, it actually occurred in some production code I am maintaining! The code was iterating through a detached DOM tree, using contents() to get at the nodes on each level, which always failed when an iframe was encountered.