let x = 50;

let y = 50;

let w = 100;

let h = 75;

​

function setup() {

  createCanvas(480, 270);

}

​

function draw() {

  if (button) {

    background(255);

    stroke(0);

  } else {

    background(0);

    stroke(255);

  }

  fill(175);

  rect(x, y, w, h);

}

​

function mousePressed() {

  if (mouseX > x && mouseX < x + w && mouseY > y && mouseY < y + h) {

    button = !button;

  }

}