​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(220);

  if (mouseX <= width / 3 && mouseY > 0 && mouseY < height) {

    fill("blue");

    rect(0, 0, width / 3, height);

  } 

  else if (mouseX <= width / 3 * 2 && mouseY > 0 && mouseY < height) {

    fill("green");

    rect(width / 3, 0, width / 3, height);

    //third column 

  } else if (mouseX <= width && mouseY > 0 && mouseY < height) {

    //only toggle the light switch when I leave the column

    fill("red");

     rect(2 * width / 3, 0, width / 3, height);

    isOn= !isOn;

  }

    // if(isOn === true); {

    //   isOn= false

//   }

//   }

//    //if the light is on, drawn a blue rectangle

//   if (isOn) {

//     fill("red");

//     rect(width / 3 * 2, 0, width / 3, height);

//   }

}