Code viewer for World: Record Save Audio
/**https://editor.p5js.org/p5/sketches/Sound:_Record_Save
 * @name Record Save Audio
 * @description Record a sound, play it back and save
 * it as a .wav file to the client's computer.
 * We need three objects: a p5.AudioIn (mic / sound source),
 * p5.SoundRecorder (records the sound), and a
 * p5.SoundFile (play back / save).
 * <p><em><span class="small"> To run this example locally, you will need the
 * <a href="http://p5js.org/reference/#/libraries/p5.sound">p5.sound library</a>
 * a sound file, and a running <a href="https://github.com/processing/p5.js/wiki/Local-server">local server</a>.</span></em></p>
 */
let mic, recorder, soundFile;

let state = 0; // mousePress will increment from Record, to Stop, to Play

function setup() {
  createCanvas(400, 400);
  background(200);
  fill(0);
  text('Enable mic and click the mouse to begin recording', 20, 20);

  // create an audio in
  mic = new p5.AudioIn();

  // users must manually enable their browser microphone for recording to work properly!
  mic.start();

  // create a sound recorder
  recorder = new p5.SoundRecorder();

  // connect the mic to the recorder
  recorder.setInput(mic);

  // create an empty sound file that we will use to playback the recording
  soundFile = new p5.SoundFile();
}

function mousePressed() {
  // use the '.enabled' boolean to make sure user enabled the mic (otherwise we'd record silence)
  if (state === 0 && mic.enabled) {
    // Tell recorder to record to a p5.SoundFile which we will use for playback
    recorder.record(soundFile);

    background(255, 0, 0);
    text('Recording now! Click to stop.', 20, 20);
    state++;
  } else if (state === 1) {
    recorder.stop(); // stop recorder, and send the result to soundFile

    background(0, 255, 0);
    text('Recording stopped. Click to play & save', 20, 20);
    state++;
  } else if (state === 2) {
    soundFile.play(); // play the result!
    saveSound(soundFile, 'mySound.wav'); // save file
    state++;
  }
}