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 ; Audio out Audio in -odac -iadc ;;;RT audio I/O ; For Non-realtime ouput leave only the line below: ; -o checkbox.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 = 10 ; nchnls = 2 instr 1 kq init 0 ; Get the value from the checkbox. k1 checkbox 1 ; If the checkbox is selected then k2=440, otherwise k2=880. k2 = (k1 == 0 ? 440 : 880) a1 oscil 10000, k2, 1 outs a1, a1 kq button 1 schedkwhen kq, 0, 1, 2, 0, 0 endin instr 2 exitnow endin </CsInstruments> <CsScore> ; sine wave. f 1 0 32768 10 1 i 1 0 1000 e </CsScore> </CsoundSynthesizer>