[Etheryte]

Why would you _want_ a synchronous, blocking script in the first place?

[kpsychwave]

For conditionally loading other blocking assets in JS.

For example, if IP is in China, local fallback for Google CDN as it will fail.

[Etheryte]

You can also do all of these things asynchronously, without blocking the whole page.

[kpsychwave]

Yes but like all async ops not without expense to the UX.