But there are some – e.g. Auszeit. And at the same time, we use ß in locations where it'd otherwise be ss. While it started as a ligature, its current usage doesn't fit that.
Interesting claim ... a similar compound word with a present-day ligature is "halfling." TextEdit renders that with an "fl" ligature, but should it not?
Absolutely true, it's not really its own letter nor is it really a ligature. It's an unique feature of the german language, which is hopefully here to stay...
Most of these actually are of latin origin. My favorite is obviously "Abszeß" - probably the only word in the german language that will show a non compounded co-existence of "sz" and "ß".
FWIW, in all of them the "sz" spans a syllable boundary (yes, even "Szene" although I despise the syllabic "S" with a vengeance because it's so awkward).
After about a year of using highcharts, for a specific custom chart project, I was given the opportunity to learn and implement it in d3. I built my first line chart by hand which took me little more than a week and then the custom chart project in about two weeks. It was definitely the most exciting project I have worked on so far.
Learning d3.js also made me rethink my 'use javascript as necessary' policy. I also came to appreciate what other charts libraries like highcharts do, but I won't be using those other libraries anytime soon if I can help it.