The support article mentions that for Linux systems, Ctrl+j is an alternate way to move focus to the search bar. Keyboard shortcuts - Perform common Firefox tasks quickly

But to address your question directly, I think the short answer is that pages may use a variety of JavaScript approach to intercept the keyboard, and I'm not aware of a setting to block that, or a universal approach to stripping custom keyboard handlers from a page, either selectively or in toto. Hmmm...

Ctrl + J is also intercepted by blogspot.com and opens a new link. Exactly the same problem as with Ctrl + K.

Is it possible to totally restrict Javascript on *.blogspot.com but to allow it on the rest of the web?

Another possible workaround is to press F6 or Ctrl+L (Ctrl+L isn't intercepted in this case) first to move the focus from the page and then Ctrl+K.

Hi dovydas, the NoScript and YesScript extensions can block JavaScript on a site-by-site basis. If you only want to block scripts on one or two sites, use YesScript (NoScript blocks on every site by default).

Thank you. I've blocked Javascript on http://googleresearch.blogspot.com with YesScript however now the web page doesn't render at all. Google hides all content from me if I disable Javascript. I've blacklisted googleresearch.blogspot.com and I am not going to dig any deeper. Let's consider this case solved. F*ck Google.

I accidentally edited that out of my reply: the Blogger templating system relies on scripting for everything.

I looked into the Dynamic Views template description and it mentions using J and K to switch between posts. Perhaps they just "forgot" to deactivate navigation when the user holds other keys down with j and k? I'm surprised, but since the page doesn't intercept Ctrl+j and Ctrl+k in Chrome, perhaps they just don't care?