let x, y, w, h;

​

function setup() {

  createCanvas(712, 400);

  // Position and size the rectangle relative to the canvas

  x = 0.37* width;

  y = 0.34* height;

  w = .13 * width;

  h = .12 * height;

}

​

function draw() {

  background(220);

  // Define the relationship between the x,y,w,h of the rectangle and its 4 sides

  let left = x - w/2;

  let right = x + w/2;

  let topp = y - h/2;

  let bottom = y + h/2;

  // Draw the rectangle

  line(left, topp, right, topp);

  line(right, topp, right, bottom);

  line(right, bottom, left, bottom);

  line(left, bottom, left, topp);

  // Move the rectangle 1/10th of the way towards the mouse

  x += (mouseX-x)/10;

  y += (mouseY-y)/10;

}