Tools/TestWebKitAPI/Tests/WebKitCocoa/audio-context-playing.html

<!DOCTYPE html>
<html>
<body>
<script>
var context;
var oscillator;
var scriptProcessor;
var isFirst = true;

function startPlaying()
{
    if (context)
        context.close();

    isFirst = true;
    return new Promise(function(resolve, reject) {
        context = new AudioContext();
        oscillator = new OscillatorNode(context);
        scriptProcessor = context.createScriptProcessor();
        oscillator.connect(scriptProcessor);
        scriptProcessor.connect(context.destination);
        scriptProcessor.onaudioprocess = (event) => {
            if (isFirst) {
                resolve();
                isFirst = false;
            }
            let inputBuffer = event.inputBuffer;
            let outputBuffer = event.outputBuffer;
            for (let channel = 0; channel < outputBuffer.numberOfChannels; channel++) {
                let inputData = inputBuffer.getChannelData(channel);
                let outputData = outputBuffer.getChannelData(channel);
                for (let sample = 0; sample < inputBuffer.length; sample++)
                  outputData[sample] = inputData[sample];
            }
        };
        oscillator.start();
    });
}

function generateAudioInMediaStreamTrack()
{
    if (context)
        context.close();

    context = new AudioContext();
    oscillator = new OscillatorNode(context);

    const mediaStreamDestination = context.createMediaStreamDestination();
    oscillator.connect(mediaStreamDestination);
    oscillator.start();
}

function transitionAudioToSpeakers()
{
    if (context)
        oscillator.connect(context.destination);
}

</script>
</body>
</html>