Comment by karteum

For simple matrix-like effects, I use

  <canvas id="matrix" style="display:block; position: fixed; top: 0; left: 0; z-index: -100;"></canvas>
  <script type="text/javascript">
  var matrix = document.getElementById("matrix");
  var matrix_ctx = matrix.getContext("2d");
  var mletters = "01"
  var font_size = 10;
  matrix_ctx.font = font_size + "px arial";
  matrix.height = window.innerHeight;
  matrix.width = window.innerWidth;
  var columns = Math.floor(matrix.width/font_size);
  var lines = matrix.height/font_size;
  var drops_reinit_threshold = 0.975; // lower value means more frequent reinit and therefore more drops
  var drops_y = Array(columns).fill(1);
  function draw()
  {
    matrix_ctx.fillStyle = "rgba(10, 10, 10, 0.04)"
    matrix_ctx.fillRect(0, 0, matrix.width, matrix.height);
    matrix_ctx.fillStyle = "#050"; // green text
    for(var i = 0; i<columns; i++)
    {
      var letter = mletters[Math.floor(Math.random()*mletters.length)];
      if (drops_y[i]*font_size <= matrix.height)
        matrix_ctx.fillText(letter, i*font_size, drops_y[i]*font_size);
      else if(Math.random() > drops_reinit_threshold)
        drops_y[i] = 0;
      drops_y[i]++;
    }
  }
  for(var x = 0; x < 2*lines; x++) draw();
  setInterval(draw, 35);
  </script>