Crash bug in Video component on IE11 when using Kerouac theme

[jalefkowit]

I have encountered what appears to be a browser-crashing bug when accessing a site using the Aesop Video component and the Kerouac theme via IE11 on Windows 10. When any page on a Kerouac-themed site that includes a video component is loaded via that browser/OS combination, IE immediately crashes. I have been able to reproduce this behavior consistently on a clean test installation of WP.

Steps to reproduce:

1. Install a clean copy of WordPress.
2. Install the Aesop Story Engine plugin.
3. Install the Kerouac theme.
4. Update the settings in Appearance > Themes to apply the Kerouac theme to the site.
5. Create an empty page.
6. Insert an Aesop video component into the empty page. (I've been using YouTube sources for this; not sure if the same problem would manifest with other sources.)
7. Save/publish page.
8. Copy URL of page published in step 7.
9. Paste URL into an up-to-date copy of IE 11 on Windows 10; hit Enter to load.
10. Watch the browser crash.

This issue only manifests itself on that one particular combination of IE 11 + Windows 10. IE 11 on Windows 8.1 does not appear to be affected; neither is any version of Edge on Windows 10.

I have tracked the issue far enough to be able to say with some confidence that it's coming from some kind of interaction between two files. These are:

1. /public/assets/js/ai-core.min.js in the Aesop plugin; and
2. /inc/misc_functions.php in the Kerouac theme.

On the file from Kerouac, the specific function within it that triggers the problem is the function kerouac_get_pagination(). If that function is commented out, or if Aesop core is modified to not load ai-core.min.js, pages with the video component can be loaded without crashing the browser. But if both are present, the browser will crash.

(Note that this only happens 100% consistently if both are active the first time an attempt is made to load the page. If, for instance, you comment out the wp_enqueue_script call for ai-core.min.js and load the page, then uncomment it and load the page again, it will sometimes load without problems.)

Based on the fact that, if the page is loaded without ai-core.min.js, the video loads but in a very small window, my half-educated-guess is that there's a problem with the FitVids responsive-video library ai-core.min.js uses that is only presenting under this very particular set of conditions. I haven't been able to get farther than that in running the bug down, and since my JavaScript expertise is moderate at best I may not be the right person to take it further. But I felt like I had enough at this point to at least be able to write up a detailed bug report, and since the issue completely crashes the browser I wanted to bring it to your attention.

Hope this is helpful! if there's any other info I can provide to help you isolate and fix the problem, just let me know.

[jalefkowit]

Update: I get reports of the same crash behavior on Windows 7 + IE 11, though I have not yet been able to replicate that.