Here\'s my issue - I need to dynamically download several scripts using jQuery.getScript() and execute certain JavaScript code after all the scripts were loaded, so my plan
To be clear, the browser JS implementation is not multithreaded.
The language, JS, can be multi-threaded.
The question does not apply here however.
What applies is that getScript() is asynchronous (returns immediately and get's queued), however, the browser will execute DOM attached content sequentially so your dependent JS code will see them loaded sequentially. This is a browser feature and not dependent on the JS threading or the getScript() call.
If getScript() retrieved scripts with xmlHTTPRequest, setTimeout(), websockets or any other async call then your scripts would not be guaranteed to execute in order. However, your callback would still get called after all scripts execute since the execution context of your 'len' variable is in a closure which persists it's context through asynchronous invocations of your function.