Why islands scripts are pushed to opts.imports?

[pazguille]

Hi,

I would like to understand because there are performance improvements about how scripts are loaded. Currently, the script have more importance than LCP images.

The scripts download, parse and execute blocking the render. Maybe, they could be loaded as modulepreload using opts.preloads instead of opts.imports.

Current:

Removing scripts from opts.imports:

[lucacasonato]

To preload them. Not all browsers support modulepreload unfortunately.

[pazguille]

Ok! We could add the defer attribute on these scripts to not block the HTML parser: https://v8.dev/features/modules#defer

What do you think?

Also add an option to use preloads instead imports.

[lucacasonato]

type=module is async by default.

[pazguille]

You are right. I missed the type="module" here: https://github.com/denoland/fresh/blob/main/src/server/render.ts#L346

[lucacasonato]

If you look at the waterfall in DevTools you should notice that the script tags are not actually blocking anything. They just show up first in the network panel because the requests are sent off first (because they are encountered by the HTML parser first).