This script adds a button (labeled "F") to the reply box in the WaniKani forum. Clicking this button switches between 3 modes:
- off: nothing happens
- on: furigana is added as soon as an entry has been chosen in the IME.
- blur: same as on, but the furigana is marked as spoiler - so it is blurred until clicked
Since this script uses your input as furigana, you have to write the whole word before selecting an entry from the IME. If you stop at ふりが and then select 振り仮名 from the IME suggestions, you will get
振り
仮名.
You can also use markup: <漢字>[かんじ] results in
漢字, and <漢字>{かんじ} puts the furigana in a spoiler tag.
For more information about the script see
https://community.wanikani.com/t/39109