An excerpt from Page 18 Third Edition, about Async attribute:

"The purpose of specifying an async script is to indicate that the page need not wait for the script to be downloaded and executed before continuing to load"

I have found a couple of resources/articles that show that the page does need to wait for async scripts to be executed (not downloaded) to continue the parsing:

source 1:
http://www.growingwiththeweb.com/201...ttributes.html

source 2:
https://m.genbetadev.com/javascript/...defer-vs-async

So, does async scripts block the parsing when being executed, or not?

Thanks!