Ejercicio 2:

Mouse trail: a series of images that would follow the mouse pointer as you moved it across the page.

<style>
    .trail {
        position: absolute;
        height: 5px; width: 5px;
        border-radius: 4px;
        background: black;
    }
    body {
        height: 300px;
    }
</style>
<body>
    <script>
    var dots = [];
    for (var i = 0; i <= 10; i++) {
      var node = document.createElement("div");
      node.className = "trail";
      document.body.appendChild(node);
      dots.push(node);
    }
    var currentDot = 0;
    
    addEventListener("mousemove", function(event) {
      var dot = dots[currentDot];
      dot.style.left = (event.pageX - 3) + "px";
      dot.style.top = (event.pageY - 3) + "px";
      currentDot = (currentDot + 1) % dots.length;
    });
  </script>