>>tonton+(OP)
I find it fascinating that it uses a 2-9 scale to grade difficulty.

The rating is described as a rating "1 - 10"

But every trick is actually graded 2 to 9. ( https://libraryofjuggling.com/TricksByDifficulty.html )

Presumably no-one ever wanted to define a grade 1, just in case an easier one was discovered, and similarly for 10.

>>tonton+(OP)
As a Java developer, I recommend Factory trick. Simple, but impresses people the most

https://libraryofjuggling.com/Tricks/3balltricks/Factory.htm...

>>tonton+(OP)
Perhaps of interest: I came across this retrospective of the author of that site and how he moved it to static hosting a couple of years ago [1].

I would also say that this library covers more or less the “lower half” of solo ball juggling in terms of difficulty. With lower ball counts (say ≤ 4), there are a lot of these patterns that have complex arm movements and can be difficult to explain with words, so having such a listing with animations and step-by-step instructions is very valuable. Starting with 4 balls, there’s less and less time for moving your arms around and it is more about the sequence of heights of the throws, which are well described with just their numeric “siteswap” pattern and you can learn them just from knowing the number sequence. The site has only the most basic of those (e.g. 534) and even very common 4-ball (7531, 633) patterns are missing with hardly anything beyond that.

[1]: https://ianconvy.github.io/projects/other/libraryofjuggling/...

>>Someon+261
> you either have to decrease the time between catching a ball and throwing it again or increase the time a ball is in the air

I think you might be thinking of 5 ball juggling.

4 ball juggling (or at least it's most common variant, "The Fountain" [0]) is fascinating because it's really juggling two balls in each hand in a way that makes it appear similar to the standard cascade. Though this may sound "less hard" than what people initially imagine, it's a very different feeling than all the basics you learn using only 3 balls.

0. https://en.wikipedia.org/wiki/Fountain_(juggling)

>>crysta+yp1
They're not wrong. Assuming alternating hands are doing the throwing (rather than both hands throwing a ball simultaneously), 4-ball patterns mean each ball is in the air for 4 beats, while 3-ball patterns only take 3 beats each.

And once one realises that many juggling patterns can be understood by the number of beats each ball takes to return to a hand, one can then think in siteswap (https://juggle.fandom.com/wiki/Siteswap).