Hide Furigana for known Kanji

parse_ankigrid.py

#!/usr/bin/python
# SPDX-FileCopyrightText: 2026 tippfehlr <tippfehlr@tippfehlr.dev>
# SPDX-License-Identifier: MIT
#
# Export KanjiGrid as json, and use this script to generate a _known_kanji.js from it.
# Place _known_kanji.js in Anki’s collection.media folder and include it with
# <script src="_known_kanji.js"/>
# in the card template html.

import json
import argparse

parser = argparse.ArgumentParser("parse_anki_grid.py")
parser.add_argument("kanjigrid", help="The kanjigrid file.", type=str)
parser.add_argument('--min-interval', help="The minimum average inteval of cards.", type=int, default=180)
parser.add_argument('--min-seen', help="The minimum number of seen cards.", type=int, default=1)
parser.add_argument('--no-unseen', help="Don’t consider kanji with unseen cards known.", type=bool, default=False)
parser.add_argument('-o', '--output', help="Where to save the javascript file.", type=str, default="_known_kanji.js")
parser.add_argument('-a', '--add', help="Additional Kanji to hide furigana for.", type=list, default="")

args = parser.parse_args()

with open(args.kanjigrid, "r", encoding="utf-8") as f:
	data = json.load(f)

units = data["units"]

known_kanji = []

for kanji, values in units.items():
	avg_interval = values[2]
	seen = values[3]
	unseen = values[4]

	is_known = (
		avg_interval >= args.min_interval and
		seen >= args.min_seen and
		(not args.no_unseen or unseen == 0)
	)

	if is_known:
		known_kanji.append(kanji)

for kanji in args.add:
    if kanji != ',':
        known_kanji.append(kanji)

known_kanji = sorted(known_kanji)

js_content = """function hideKanji() {
		// Known kanji from Kanji Grid
		const knownKanji = new Set([%s]);

		// Hide furigana for known kanji
		const rubyElements = document.querySelectorAll("ruby");

		rubyElements.forEach(ruby => {
			const firstNode = ruby.childNodes[0];
			if (!firstNode) return;

			const kanjiChar = firstNode.textContent.trim();
			const rtTag = ruby.querySelector("rt");

			if (kanjiChar && rtTag && knownKanji.has(kanjiChar)) {
				rtTag.style.display = "none";
				}
			});
		}
hideKanji();
""" % ",".join(f'"{k}"' for k in known_kanji)

with open(args.output, "w", encoding="utf-8") as f:
	f.write(js_content)

print(f"Exported {len(known_kanji)} kanji to {args.output}")