How to map key to empty and pass keystroke to browser on specific websites

[krulshark]

I would like to achieve the default behavior for j and k on the duckduckgo search results page, which allows the user to navigate through the list of search results with j/k and use enter to open.

I have attempted mapping j and k like so:

env ddg host="duckduckgo.com.*"
env nddg host="^(?!.duckduckgo.com).*"

map j runKey expect=[{"env":"ddg","keys":"<ddgj>"},{"env":"nddg","keys":"<nddgj>"}] keys="<v-j>"

map <ddgj> blank
map <nddgj> scrollDown

But the blank mapping doesn't give the browser the keystroke, so it just does nothing on duckduckgo, and using mapKey similarly doesn't work.

I'm probably overlooking something obvious, but I've spent like 90 minutes now trying to figure this out and am about ready to give up, so any help would be much appreciated!