Internet Explorer - CORS not supported

[paul90]

Internet Explorer version 8 and 9 don't support Cross-Origin Resource Sharing (CORS). This causes XMLHttpRequests to domains other than that hosting the page to be blocked in the browser.

This results in content on other sites within the federation not being known about, as the fetch of the sitemap will not have happened, so the user will be given the option to create a new blank page.

There is a relatively simple fix, to add a JScript plugin to add support for XDomainRequest.

I have a fix candidate in my win-ie branch - for the Sinatra server.

This adds Modernizr together with its CORS test plugin, and updates JQuery version.

This will need testing, so no pull request yet. Also possible that the JQuery update is not needed, and can be done later.

Summary of XHR2 CORS (or rather lack of) in Internet Explorer

• IE 6, 7, 8, and 9 do not support XHR2 CORS. It is not possible to make generalized cross-domain requests in these browsers.
• IE 8, 9 support an ActiveX control called XDomainRequest that only allows limited cross-domain requests compared to XHR2 CORS.
• IE 10 supports XHR2 CORS.

[WardCunningham]

Thank you for exploring this.

I've been told that the work we've been doing might not ever run on anything less than IE 10. I've used that as an excuse for ignoring this and other compatibility issues. I know that this "luxury" can't last. However, I suspect we will run into javascript engine issues for which there are no easy work arounds as we go further back in any line of browser implementations.

[paul90]

Unfortunately it been a problem for a very long time, with different browsers working in different ways. Though thankfully nowhere as bad as it was some years ago.

It would be good to support all the currently supported browsers - though it has been a few years since I took to good a look. It will however include IE 9 ( IE 10 has not yet been released for Win 7 - which is still out shipping Win 8).

In part this is behind adding in the Modernizr library - for checking feature support (not browser version), and being able to add in support where it is needed.

Not sure how far back we may want, or need, to go back in any of the browser lines. Hopefully not too far, and definitely not back to versions that are no longer supported.

[paul90]

Currently 25 mocha tests fail with IE 9, but the same results with the master branch - though some of that may be because it is rendering the test page using 'quirks' mode.

Some of the other errors look to be a know mocha issues, so will updating the mocha version.

[paul90]

Code to resolve this was rolled into #368