Reproducing BingPreview JavaScript errors

Question

I have a website that gets visits from BingPreview/1.0b*, which is likely a bot for Bing.

I'm getting an error that looks like it can't find a DOM Element that I'm pretty sure should exist. I'm not getting errors from any other browsers (tested in all major browsers) or bots (although lack of errors doesn't necessarily prove anything).

My most likely explanation is that it's executing JavaScript before the document has been fully loaded but I don't know how to reproduce a BingPreview bot visit.

How do I reproduce BingPreview visits / JavaScript errors?

* Full UA-string is: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534+ (KHTML, like Gecko) BingPreview/1.0b

Notes: The visit occured 3 days ago, everything I can find about BingPreview seems that it's not publicly available anymore (dead links and such)

Answer 1

First, The user agent is, as you presumed, some sort of Bot for Bing. There have been questions like this one which suggest that Microsoft have been testing some sort of Page Preview for their search results, similar to google's.

Because it is them testing and their implementation of the bot (the bot's javascript engine) that most likely caused errors, there's also most likely no way for you to reproduce it.

What you can surely do is set your User agent string in Chrome in the dev console to the Bing Bot UA and see if something happens, because then you have the same user agent and, as it looks from the UA, the same engine (Webkit). Bot most likely, nothing will happen, because if something is wrong there, it is them doing undisclosed testing on your site.

EDIT

There's also this post on webmasterworld, suggesting that is actually some sort of preview feature, which has also been seen on the bing results pages, but in random manner. I cannot confirm it, Bing for me looks the same as always, without previews.

SECOND EDIT

And Microsoft themselves do not seem too keen on replying