Feature Adding AssetPipeline & ImportMaps

[crimson-knight]

Description of the Change

This is a big step forward in modern JS for Amber!

This change adds the new import maps feature and the asset_pipeline shard for new apps by default. This also has some minimal updates to get the existing client_reload feature working and get the

Benefits

• No build step during deployments, but allows JS locally and from CDNs (npm, etc.)
• This fingerprints asset files so when files change, the links/references to the files are automatically updated to more easily break any browser caching that is configured.

Possible Drawbacks

Using module-based JS does require a different approach than what most backend devs are probably comfortable with. If you're accustomed to the standard of just putting plain JS into a file and it executes on it own, this is going to be a bit different.

[drujensen]

lgtm. 💯 one suggestion is to use assets directory instead of src for familiarity by Rails developers.

[drujensen]

wdyt of assets/javascript instead?

[crimson-knight]

I kicked that around. If the deployment doesn't require the entire code base be cloned, then it makes total sense.
But, wouldn't most dockerized/containerized deploys mean the entire code base was cloned into the image and then deployed?

[drujensen]

I would just copy the assets directory to the docker image instead of src/javascript. I think it will actually make creating the image easier.

[hugopl]

A bit cosmetic, but maybe a helper function like import_map_tag instead of a constant declared in the initializer could hide a bit of implementation details here.

If the plan is to have import maps as a built in feature, maybe would be worth to deal with it like Amber does with routes and settings, a file config/import_maps.cr with:

Amber::Server.import_maps(source_dir: "src/javascript", output_dir: "public") do |import_maps|
  ...
end

OR, to not fill Amber::Server with frontend stuff:

Amber::ImportMaps.configure(source_dir: "src/javascript", output_dir: "public") do
...