Here are the new elements in use, its basically a modification of the PD example C08.analog.sequencer.pd: https://arrays.handmadeproductions.de/

I thought maybe it is a good idea to collect Emscripten behavior / bugs that differ from Ofelia without Emscripten.

Five things for now:

[cos~] does not work, [expr~ cos(2 * 3.14159 * $v1)] does.
[array] does not work, but [array define] does.
ofSetLineWidth() does not work.
I need to set the ticksPerBuffer in ofApp.cpp from 8 to between 16 and 64, depending on the complexity of the patch and the power of the computer for avoiding audio glitches and artifacts (maybe there is a way to optimize it).
Shader need to be ported from GLSL to GLES or directly written in GLES.

@ostorni redarding audio latency: this is the shortest audio latency without artifacts that seems to work for me, sadly its still around 100-200 ms (also depending on the complexity of the patch)... Its really nice that the Pure Data audio stuff can run in a browser, but would be much better if the latency could be improved...

https://simplesequencer.handmadeproductions.de/

Here is something about the (not yet implemented) audioWorklet technology, which sounds quite promising (not sure, if OF could be a another bottleneck in this case): https://hacks.mozilla.org/2020/05/high-performance-web-audio-with-audioworklet-in-firefox/

Another drawback: While it seems to work very well on my desktop computer, my Android phone seems to be too slow for the Emscripten stuff...

@ostorni Sounds very interesting, but never used gdpd. In my opinion Ofelia with Emscripten is relatively painless regarding some basic stuff, but it has its quirks (mainly due to using Open GL ES instead of Open GL) and issues that are solvable with enough experience, I guess (some things I just do not understand...). Still, it has a lot of potential if its developed further (I started to implement WebMIDI for example, which works quite well, but is coded in a messy way)... Also audio latency could be improved using AudioWorkletNode instead of ScriptProcessorNode... I think there are also some issues with the current OF / Emscripten combination, that are possibly solved in the future (already opened a few Github issues)...

@jaffasplaffa now also with a knob (with Emscripten it is not antialiased because of an unknown bug, but with Ofelia it is)...
https://github.com/Jonathhhan/Pure-Data-Ofelia-Emscripten/tree/main/pure data gui with font - expanded
As a side note: ofSetLineWidth() does not seem to work with Emscripten. Possibly an issue with OpenGL ES: https://stackoverflow.com/questions/24494495/opengl-es-line-thickness
edit: I combined the multislider with ofArray (in the ofelia_arraySlider abstraction...), which means the interface is directly connected to a PD array.

Now with an XY-pad and a variant of the slider...
pure data gui with font - expanded.zip

edit: also updated the emscripten version: https://puredatagui.handmadeproductions.de/

What kind of GUI elements do you think are missing (I have a XY-pad in mind) or could be optimized?

I made a multislider for Ofelia v4, its in the style of the other GUI elements. I made one once for Ofelia v2, but that isnt compatible for v4. There are some things that need to be optimized, maybe it would be nice to combine it with the functionality of ofArray(). But the interpolation of values does work now (that was the most difficult part for me...).
pure data multiSlider with font.zip

@ddw_music you can put a float into the left inlet with the seed message.

it is also possible with ofelia / lua : https://forum.pdpatchrepo.info/topic/12057/ofelia-lua-script-abstractions