title: p5.js Old frames not deleting
body: <p>Using a javascript framework called p5, I'm trying to animate a circle that moves across the screen, however old frames don't delete, and this causes a line to show across the canvas.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var xPos = 0;
  
  function setup() {
      createCanvas(400, 200)
      background(123);
  }
  
  function draw() {
      ellipse(xPos, height/2, 30, 30); //Draws the circle
      fill(255);
      xPos++; //Moves the circle a pixel over
      if(xPos &gt; width){xPos = 0;} //resets the circle when it reaches the edge of the canvas
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="http://cdnjs.cloudflare.com/ajax/libs/p5.js/0.5.5/p5.js"&gt;&lt;/script&gt;</code></pre>
  </div>
  </div>
  </p>