Test simple tone and gain processor

A simple sinewave with gain control. [You might need to clean the cache when you are testing your worklet processor code]

    class CustomProcessor extends AudioWorkletProcessor {

      static get parameterDescriptors() {
        return [{ name: 'gain', defaultValue: 0.1 }];
      }

      constructor() {
        super();
        this.sampleRate = 44100;

        this.port.onmessage = (event) => {
          console.log(event.data);
        };
      }

      process(inputs, outputs, parameters) {

        const speakers = outputs[0];
        for (let i = 0; i < speakers[0].length; i++) {

          const func = Math.sin(i) + 0.4;
          const gain = parameters.gain[i];
          speakers[0][i] = func * gain;
          speakers[1][i] = func * gain;
        }
        return true;
      }
    };
  

    let audioContext = new AudioContext();
    let customNode;
    let customProcessorName = 'custom-processor';
    let customNodeName = 'custom-node';
    let workletUrl = 'custom-processor.js';

    class CustomAudioNode extends AudioWorkletNode {

      constructor(audioContext, processorName) {

        super(audioContext, processorName, {
          numberOfInputs: 0,
          numberOfOutputs: 1,
          outputChannelCount: [2]
        });
      }
    }


    document.addEventListener("DOMContentLoaded", () => {
      setButtonEventHandlers();
    });

    function setButtonEventHandlers() {

      const playButton = document.getElementById('playButton');
      playButton.addEventListener("click", () => playAudio());

      const stopButton = document.getElementById('stopButton');
      stopButton.addEventListener("click", () => stopAudio());

      const plusButton = document.getElementById('plusButton');
      plusButton.addEventListener("click", () => increaseVolume());

      const minusButton = document.getElementById('minusButton');
      minusButton.addEventListener("click", () => decreaseVolume());
    }

    function playAudio() {
      try {
        // window.CustomAudioNode = audioContext.audioWorklet.addModule(workletUrl).then(() => {
        window.CustomAudioNode = audioContext.audioWorklet.addModule(workletUrl).then(() => {
          stopAudio();
          customNode = new CustomAudioNode(audioContext, customProcessorName);

          customNode.port.onmessage = (event) => {
            // Handling data from the processor.
            console.log("from processor: " + event.data);
          };

          customNode.connect(audioContext.destination);
        });
      } catch (err) {
        console.log("AudioWorklet not supported in this browser: ", err.message);
      }
    }

    function stopAudio() {
      if (customNode !== undefined) {
        customNode.disconnect(audioContext.destination);
        customNode = undefined;
      }
    }

    function increaseVolume() {
      if (customNode !== undefined) {
        const gainParam = customNode.parameters.get('gain');
        gainParam.value += 0.1;
      }
    }

    function decreaseVolume() {
      if (customNode !== undefined) {
        const gainParam = customNode.parameters.get('gain');
        gainParam.value -= 0.1;
      }
    }