createCanvas(400, 400);

}

​

function draw() {

  fill(0);

  noStroke();

  drawdot(mouseX, mouseY);

  clearbutton();

​

}

function drawdot(x,y){

  ellipse(x,y,5);

}

​

function clearbutton(){

  fill(255);

  stroke(0);

  ellipse(20,20,40);

  if((mouseX>= 0 && mouseX <= 40) && (mouseY>= 0 && mouseY <= 40) && mouseIsPressed){

    background(255);  

  }

  fill(0);

}

​