Trying to access Class names in global context

StackOverflow question: https://stackoverflow.com/questions/66287396/accessing-api-class-names-in-global-context

HTML

<html>
    <head>
        <title>Accessing API Classes</title>
    </head>
<body>
    <h2>MWE for attempting to access API class names</h2>

    <p>I can access various classes from DevTools and programmatically
       yet I can't see them as attributes of <code>window</code> object.</p>

    <p>Turn on DevTools to see this example</p>

<script>


console.log('typeof window.ArrayBuffer:', 
        typeof window.ArrayBuffer);
console.log("window.hasOwnProperty('ArrayBuffer'):", 
        window.hasOwnProperty('ArrayBuffer'));

let c = 0;
for (let n in window) {
    //console.log(n);
    if (n == 'ArrayBuffer') {
        console.log('FOUND: ArrayBuffer');
    }
    c++;
}
console.log(c + ' attributes checked')

</script>
</body>
</html>