AudioContext.createScriptProcessor()

var audioCtx = new AudioContext();
myScriptProcessor = audioCtx.createScriptProcessor(
  bufferSize,
  numberOfInputChannels,
  numberOfOutputChannels,
);

var myScript = document.querySelector("script");
var myPre = document.querySelector("pre");
var playButton = document.querySelector("button");

// Create AudioContext and buffer source
var audioCtx = new AudioContext();
source = audioCtx.createBufferSource();

// Create a ScriptProcessorNode with a bufferSize of 4096 and a single input and output channel
var scriptNode = audioCtx.createScriptProcessor(4096, 1, 1);
console.log(scriptNode.bufferSize);

// load in an audio track via XHR and decodeAudioData

function getData() {
  request = new XMLHttpRequest();
  request.open("GET", "viper.ogg", true);
  request.responseType = "arraybuffer";
  request.onload = function () {
    var audioData = request.response;

    audioCtx.decodeAudioData(
      audioData,
      function (buffer) {
        myBuffer = buffer;
        source.buffer = myBuffer;
      },
      function (e) {
        "Error with decoding audio data" + e.err;
      },
    );
  };
  request.send();
}

// Give the node a function to process audio events
scriptNode.onaudioprocess = function (audioProcessingEvent) {
  // The input buffer is the song we loaded earlier
  var inputBuffer = audioProcessingEvent.inputBuffer;

  // The output buffer contains the samples that will be modified and played
  var outputBuffer = audioProcessingEvent.outputBuffer;

  // Loop through the output channels (in this case there is only one)
  for (var channel = 0; channel < outputBuffer.numberOfChannels; channel++) {
    var inputData = inputBuffer.getChannelData(channel);
    var outputData = outputBuffer.getChannelData(channel);

    // Loop through the 4096 samples
    for (var sample = 0; sample < inputBuffer.length; sample++) {
      // make output equal to the same as the input
      outputData[sample] = inputData[sample];

      // add noise to each output sample
      outputData[sample] += (Math.random() * 2 - 1) * 0.2;
    }
  }
};

getData();

// wire up play button
playButton.onclick = function () {
  source.connect(scriptNode);
  scriptNode.connect(audioCtx.destination);
  source.start();
};

// When the buffer source stops playing, disconnect everything
source.onended = function () {
  source.disconnect(scriptNode);
  scriptNode.disconnect(audioCtx.destination);
};