​

function setup() {

  song = loadSound('sound/intmus3.mp3');

  createCanvas(400,400);

  background(255,0,255);

}

​

function mousePressed() {

  if ( song.isPlaying() ) { // .isPlaying() returns a boolean

    song.stop();

    var r = random(0,255);

    var b = random(100,255);

    background(r,0,b);

  } else {

    song.play();

    background(100,100,100);

  }

}

​