Why does _evalUrl() use async:false?

Why does _evalUrl() use async:false?

Why does _evalUrl() use async:false? Would it ever make sense for it to use async: true? Does it affect the user experience at all?

My guess is that by doing it synchronously rather than async, you guarantee that javascript files are loaded and executed in order. Is that the reason?

A common question when using jQuery is: Why am I seeing this warning: "Synchronous XMLHttpRequest on the main thread... jquery.js?body=1:9628"?

The answer is that they are inserting a new <script> tag to the HTML via jQuery, and then jQuery loads the external script file src synchronously.