API: save a "flag" on window object (#474)

We need to find a way for people subscribing to the Read the Docs data
ready event _after_ it was triggered. This is an idea about how to solve
this use case.

It adds a "flag" in the `window` object that users can check _before_
subscribing to that event to make usage of the data if the event was
triggered already.

* Reference:
readthedocs/readthedocs.org#10648 (comment)
* Example:
https://github.com/readthedocs/test-builds/blob/full-feature/docs/static/readthedocs.js

Author: humitos

src/readthedocs-config.js

@@ -114,6 +114,10 @@ export function getReadTheDocsConfig(sendUrlParam) {
           // Expose `dataUser` if available or the `data` already requested.
           const dataEvent = dataUser !== undefined ? dataUser : data;
 
+          // Add the data to the window so scripts loaded after the initial
+          // event was fired can still get access to the data
+          globalThis.ReadTheDocsEventData = new ReadTheDocsEventData(dataEvent);
+
           // Trigger the addons data ready CustomEvent to with the data the user is expecting.
           return dispatchEvent(
             EVENT_READTHEDOCS_ADDONS_DATA_READY,