let slider, button;

​

function setup() {

  createCanvas(400, 400);

  // Create a slider and place it at the top of the canvas.

  slider = createSlider(0, 255);

  slider.position(10, 10);

  slider.size(80);

  button = createButton('Toggle Send');

  button.position(10, 40);

}

​

function draw() {

  // Use the slider as a grayscale value.

  let g = slider.value();

  background(g);

  button.mousePressed(toggleSend);

  if (shouldSend) {

    console.log(g);

  }

}

​

function toggleSend() {

  shouldSend = !shouldSend;

}