webxr/resources/webxr_check.html

<script src=webxr_util.js></script>
<script>
'use strict';
let definedObjects = [];
let undefinedObjects = [];

forEachWebxrObject((obj, name) => {
    if(obj == undefined) {
        undefinedObjects.push(name);
    } else {
        definedObjects.push(name);
    }
});

window.parent.postMessage({ undefinedObjects, definedObjects}, '*');

</script>