I am having trouble with my javascript animation
<p>I am trying to animate using a sprite sheet and use it in my website, however I am knew to animation and I am having some trouble fixing it, currently nothing shows up on my webpage when I use this. I am using a sprite sheet which is called Speech.png, is 18176 x 256 and each frame is 256x256. Here is my code so far.</p>

<pre><code>&lt;script language="javascript"&gt;
    // screen size variables
    var SCREEN_WIDTH = window.innerWidth,
    SCREEN_HEIGHT = window.innerHeight;        

    var canvas = document.createElement('canvas');
    var c = canvas.getContext('2d');

    canvas.width = SCREEN_WIDTH;
    canvas.height = SCREEN_HEIGHT;

    var xpos=0, 
        ypos=0, 
        index=0, 
        numFrames = 70, 
        frameSize= 255;

    // Add our drawing canvas
    document.body.appendChild(canvas); 

    //load the image
    image = new Image();
    image.src = "Speech.png";

    image.onload = function() {
        //we're ready for the loop
        setInterval(loop, 1000 / 30);
    }

    function loop() {
        //clear the canvas!
        c.clearRect(0,0, SCREEN_HEIGHT,SCREEN_WIDTH);

        /*our big long list of arguments below equates to: 
            1: our image source
            2 - 5: the rectangle in the source image of what we want to draw
            6 - 9: the  rectangle of our canvas that we are drawing into

                the area of the source image we are drawing from will change each time loop() is called.
                the rectangle of our canvas that we are drawing into however, will not. 
                tricky!
        */
        c.drawImage(image,xpos,ypos,frameSize,frameSize,0,0,frameSize, frameSize);

        //each time around we add the frame size to our xpos, moving along the source image
        xpos += frameSize;
        //increase the index so we know which frame of our animation we are currently on
        index += 1;

        //if our index is higher than our total number of frames, we're at the end and better start over
        if (index &gt;= numFrames) {
            xpos = 0;
            ypos = 0;
            index = 0;    
        //if we've gotten to the limit of our source image's width, we need to move down one row of frames                
        } else if (xpos + frameSize &gt; image.width){
            xpos =0;
            ypos += frameSize;
        }      
    }
&lt;/script&gt;
</code></pre>