Support jsbundling

[jorgemanrubia]

Add supports for JS bundling:

• Detects jsbundling and configures a compatible setup. When a JS file changes, it will reload the HTML instead of reloading the controller that changed. Hot reloading is not possible in the browser as it won't resolve the dependencies outside of the bundling environment.
• This also reworks the approach to reload stimulus controllers. Instead of parsing the importmaps entry, the engine will expose an endpoint to fetch the source of changed assets. The Stimulus reloader will fetch the changed javascript files using that endpoint so that it won't depend on importmaps anymore.
• Add options to configure the handled extensions for each kind of change.

Closes #12

[kobaltz]

I was playing around with this branch and noticed in a very simple jsbundling - esbuild example, the HTML changes will trigger and reinitialize the stimulus controllers! Really cool! ❤️

I also noticed that if you try to modify the stimulus controller (the default hello controller in this example), then it will cause a javascript error.

My steps to reproduce this is basically creating a new esbuild/bootstrap Rails 8 application with propshaft and add the hotwire-spark gem.

group :development do
  gem "hotwire-spark", github: "hotwired/spark", branch: :jsbundling
end

Add the stimulus controller in a simple scaffolded page.

<h1>Welcome#index!!!!</h1>
<p>Find me in app/views/welcome/index.html.erb</p>

<div data-controller="hello">STIMULUS CONTROLLER</div>

And then try to make a change to the text in the hello stimulus controller.

[jorgemanrubia]

Thanks @kobaltz. Yes, I found that issue too. I like the change but this needs more work. Reloading individual classes is not as easy as with import maps as modules can't be resolved by the browser... unless we used importmaps to define them 😅. I still like the change independently of this since it lets us reload JS files faster (without an additional request to reload the html document), but I need to play more with the jsbundling scenario.

[nickjj]

I wanted to mention this is working quite nicely for the basic tests I ran with Rails 8 using jsbundling, Propshaft and Spark v0.1.10.

• Install Spark
• Open page with Stimulus controller
• Make a change, such as adding console.log("hello") to a piece of JS
• Do the thing on the page that invokes that piece of JS
• See hello emit in the console
• Remove that console.log("hello") line
• Do the thing on the page that invokes that piece of JS
• No longer see the console output being emit
• Change text within a Stimulus controller
• I didn't observe any console errors