It's been a while since the last example, finally managed to get back to this, so today we'll look at the Forward And Backward Reaching Inverse Kinematics (FABRIK) algorithm. It's a really nice and easy to understand algorithm, easy to implement and can have a lot of uses (such as implementing it for full body IK solvers, adding constraints, etc)
But here I'm showing it in a simple form

Here's the sketch
https://editor.p5js.org/admiralra/sketches/FBRwrPqbF

And here are a few examples I made a few years ago.

Made in Bifrost for Maya:
https://www.artstation.com/artwork/58RgB1
And another written in Lua on the Ipad:
https://www.artstation.com/artwork/X1d6Wl