I\'m wondering if it\'s possible to execute some javascript inside an ld+json script. For example \"window.location.hostname\"
No, scripts of the type "application/ld+json" won't be executed. But, you could do something like this:
<script>
var el = document.createElement('script');
el.type = 'application/ld+json';
el.text = JSON.stringify({
"@context": "http://schema.org",
"@type": "WebSite",
"url": "http://" + window.location.hostname
});
document.querySelector('body').appendChild(el);
</script>