Support for IE8 when document.domain is set

[danjamin]

In relation to issue #150 -- took commit 4f738ac and applied it to es5-sham

Basically, the problem is that in IE < 9, when document.domain is set, using the es5-sham causes a "Permission denied" error. What this fix does, is uses a different approach to the Object.create polyfill when this situation arises. It leaves the original iframe approach intact for all other cases.

For those of us still supporting IE8 😩, and where document.domain is necessary for an API being used via iframes (x-origin reasons), this fix should allow es5-sham to be used without error.

[ljharb]

Should this if (!document.domain) { return false; } on the first line of the function, to avoid the try/catch when it's not set?

[danjamin]

Agreed 👍

[ljharb]

This is great - I suspect this can't be tested for without making a separate HTML file, since document.domain can't be unset once set?

[danjamin]

@ljharb agreed that testing this specific edge case might be a bit tricky given the IE8 environment and document.domain needing to be set

[ljharb]

@danjamin It would be super helpful if you could set up a jsfiddle, that used rawgit.com to point to your PR's test file, and set document.domain so I can use it to verify in various browser versions :-) if not, i'll wait to merge it til I have time to set that up.

[danjamin]

@ljharb I'll give it a shot -- will ping you when it's ready

[ljharb]

Thanks!

[danjamin]

@ljharb turns out jsfiddle doesn't let you adjust the document.domain; so I just created a quick gh-pages for my fork; you can visit it here http://danjamin.github.io/es5-shim/

it has 2 pages (/broken and /fixed) -- if you visit both in IE8 you will see that the broken one has the "Permission Denied" error where as the fixed one does not error on the Object.create(null) invocation.

The only real difference between /broken and /fixed is that one points at es5-shim/master of es5-sham.js and the other at the version in the branch in my fork being pull requested.

[ljharb]

Awesome, that's good enough for me! https://github.com/danjamin/es5-shim/commit/c471214c1c8c4f6a1042c2ef53a0e69cf2ac5ad0 confirms it for me in my testing.

[danjamin]

Cool -- glad I could help 😃