We are currently using the Microdata format to expose data to search engines and we are looking at exposing more info to be able to support some more advanced Google Search features. As I'm working my way through the fields I'm finding I need information that we currently load asynchronously so it is not a part of the initial response.
JSON-LD looks like its what Google prefers but all the examples I've seen have it embedded in the page. Could you have a link to a JS file so it gets loaded as a separate call? Something like
<script type="application/ld+json" src="/myid123/jsonld.js"></script>
If you are using the
script element as data block, "the
src attribute must not be specified".
script element is not used as data block, it has to be "used to include dynamic scripts". But a JSON-LD document is not a dynamic script.
For linking to another resource, just like you do it with external stylesheets or Favicons, you can use the
link element in the
head (or the corresponding HTTP header):
<link href="/myid123/jsonld.js" type="application/ld+json" />
In principle, consumers could follow this reference (possibly only if a certain link type is specified), and make use of data, just like they do it with embedded JSON-LD, Microdata, or RDFa.
However, consumers don’t have to do this, of course, and many probably don’t.
Google Search in particular does not claim to support it for consuming Schema.org in the JSON-LD format. However, they claim to support "dynamically injected" JSON-LD data blocks.