As far as I can see, XMLHttpRequest calls may be synchronous or async.
Currently, async calls are loaded onto the job queue for immediate execution, blocking all other jobs, what I would call sync.
Sync calls are executed directly while the JSExecutor continues to run other scripts in a different thread, this is async in my view.
Honestly, I do not understand the entire engine, but this might produce behaviour different to real world browsers, especially if such a request times out.
As far as I can see, XMLHttpRequest calls may be synchronous or async.
Currently, async calls are loaded onto the job queue for immediate execution, blocking all other jobs, what I would call sync.
Sync calls are executed directly while the JSExecutor continues to run other scripts in a different thread, this is async in my view.
Honestly, I do not understand the entire engine, but this might produce behaviour different to real world browsers, especially if such a request times out.