loadSound for a user uploaded file

If you are wanting to use p5 then you can use the drop() method and callback the loadSound() method. Then in the success callback of the loadSound() method, play the sound …

function setup() {
  let cnv = createCanvas(400, 400);
  background(222);
  cnv.dragOver(_ => {
    background(157);
  });

  cnv.dragLeave(_ => {
    background(222);
  });

  cnv.drop(file => {
    let snd = loadSound(file.data, _ => {
      snd.play();
      p.html('playing').position(125, 100);
    });
  }, _ => {
    background(222);
  });

  let p = createP('Drag your file here ...').position(25, 100).style('font-size', '27pt');
}