index.html

<html>

<body onload="canvas.setup()">

    <canvas id="canvasArea1" style="position: absolute; left: 0; top: 0; z-index: 0; width:100%;height:100%"></canvas>
    <canvas id="canvasArea2"
        style="visibility: hidden; position: absolute; left: 0; top: 0; z-index: 0; width:100%;height:100%"></canvas>

    <script src="./canvas.js"></script>
</body>

</html>
<script>

    // Declare all global variables here
    function setup() {
        // Initialize variables here
    }

    // Declare custom functions here


    // Function while will be called repeatedly 
    function main() {
        canvas.clear();

    }

    // Override functions here; 
    canvas.mainFunction = main;

    var timeStep = 50;
    canvas.startMain(timeStep);
    canvas.setupFunction = setup;

</script>