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> ; Select audio/midi flags here according to platform -odac -M1 -Q1 ;;;realtime audio out and midi in and midi out ;-iadc ;;;uncomment -iadc if realtime audio input is needed too ; For Non-realtime ouput leave only the line below: ; -o midinoteoff.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> ; Required settings for WebAudio: sr = 48000 ksmps = 128 nchnls = 2 nchnls_i = 1 ; sr = 44100 ; ksmps = 32 ; nchnls = 2 0dbfs = 1 instr 1 ;uses external midi device kkey init 0 ;initialize key number kvel init 0 ;initialize velocity midinoteoff kkey,kvel ;MIDI noteoff value printk2 kvel ;display noteoff value midion 1, kkey, kvel ;sent note to external device endin </CsInstruments> <CsScore> f 0 30 ;runs for 30 seconds i 1 0 2 62 ; play these notes from score as well i 1 + 2 65 e </CsScore> </CsoundSynthesizer>