<script>

// DEFINE YOUR GLOBAL VARIABLES HERE

 var canvas;
  var context;

 var nf;
  nf = 10; 
  
  var inc;
  
  inc = 0;
  
  // INITIALIZE THE STARTING FUNCTION

 function init() {
  
  canvas = document.getElementById("myCanvas");
  context = canvas.getContext("2d");
  
  // CALL SUBSEQUENT FUNCTIONS, as many as you need
  
  drawBkgd(); // COVER TRANSPARENT CANVAS
  
  return setInterval(create, 50); // THIS IS WHERE AL HAPPENS
  
  }
  
  
  function drawBkgd() { // USE THIS AREA TO MODIFY BKGD
  context.fillStyle = "rgb(255,100,100)";
  context.fillRect(0,0,canvas.width, canvas.height);
  }

function clear() {
  context.clearRect(0,0,canvas.width, canvas.height);
  }
  
  function create() { 


// POSSIBILITY ONE

 /*if (nf < 100) { inc = 1; } 

 if (nf>300) { inc = -1; } 
  
  nf += inc*10;*/
  
  // POSSIBILITY TWO SINE INCREMENT

 inc += 0.1;
  
  if (inc > Math.PI *2) { inc = 0; }
  
  var nf = Math.abs(Math.cos(inc) * 100) + 10;

 var mf = context.font = "normal "+nf+"px 'Arial black'";
  
  clear();
  drawBkgd();
  
  context.fillStyle = "black";
  context.font = mf;
  context.textAlign = 'center';
  context.fillText("ART", canvas.width/2, canvas.height-nf);


  }
  
  </script>