This should play if your Web browser has WebAssembly enabled (most do). Most examples will play unless they need to load files. The first time you click Play, Csound will spend a few seconds loading, then play. You can edit this code and replay it.
<CsoundSynthesizer> <CsOptions> -odac </CsOptions> <CsInstruments> ; Required settings for WebAudio: sr = 48000 ksmps = 128 nchnls = 2 nchnls_i = 1 ; nchnls = 2 0dbfs = 1 ; ksmps = 8 ; sr = 44100 instr hdf5write aArray[] init 2,2 ; Initialise a 2 X 2 a-rate array aArray[0][0] vco2 0.2, 100 ; Fill array with vco2 signals aArray[0][1] vco2 0.4, 200 aArray[1][0] vco2 0.8, 300 aArray[1][1] vco2 1, 400 aVar vco2 0.2, 100 ; Initialise an a-rate variable with a vco2 signal kVar phasor 1 ; Initalise a k-rate variable with a phasor signal hdf5write "example.h5", aArray, aVar, kVar ; Write variables to an hdf5 file endin </CsInstruments> <CsScore> i "hdf5write" 0 1 </CsScore> </CsoundSynthesizer>