Preparing the Domain, Common

Example F.2. animate.html
<!doctype html>
<html>
    <head>
        <meta charset="utf-8"/>
        <title>Canvas Test 0</title>
        <style>
            #canvas { border: 2px solid blue; }
        </style>
        <script>
            'use strict';

            let initialize = function () {
                window.alert('Just checking');
                // your code goes here
            }
        </script>
    </head>
    <body>
        <section>
            <canvas id='canvas' width='400' height='400'>
                If you see this text long enough to read it,
                your browser is very old.
            </canvas>
        </section>
    </body>
    <script>initialize();</script>
</html>

Test it!