Use index section as resources

[hayatoito]

As Bundle Dependencies proposal briefly mentions, it would be nice that a resource listed in the index section of the bundle will be also a target of subresource loading, even if the resource is not mentioned in resources in <script type=webbundle>.

The benefit is: users don't have to list all resources in resources. They have to specify only direct dependencies.

For example, suppose that main.html is:

<script type="webbundle">
{
   source: "a.wbn",
   resources: [....]    # what should be specified?
}
</script>

<link rel="style" href="a.css" />

...

<img src="a.png" />

...

<script type="module" src="a1.js" />

The bundle, a.wbn has the following resources:

URL
./a1.js
./a2.js
./a3.js
./a.png
./a.css

The dependency graph is:

main.html
├── a1.js
│   ├── a2.js
│   └── a3.js
├── a.png
└── a.css

Then, it would be nice that users can specify only the direct dependencies in resources, as follows:

<script type="webbundle">
{
   source: "a.wbn",
   resources: ["a1.js", "a.css", "a.png"]
}
</script>

<link rel="style" href="a.css" />

...

<img src="a.png" />

...

<script type="module" src="a1.js" />

Instead of listing all resources:

<script type="webbundle">
{
   source: "a.wbn",
   resources: ["a1.js", "a2.js", "a3.js", "a.css", "a.png"]
}
</script>

<link rel="style" href="a.css" />

...

<img src="a.png" />

...

<script type="module" src="a1.js" />

We probably want to introduce an optional key in JSON of <script type=webbundle> to enable this behavior of not, however, I'm feeling that this behavior is fine as the default behavior in most cases .

[irori]

I vaguely remember that we considered using bundle's index section instead of letting the page specify the resources or scopes, although I cannot recall why we ended up with current design. The explainer has No declarative scope section for that idea.

[hayatoito]

Yeah, as far as I remember vaguely, the discussion in the past assumes "all" or "nothing". Specify all resources or specify nothing.

This issue is proposing a slightly different thing. Specify only the direct dependencies beforehand. Regarding indirect dependencies, we can use index section information, in theory.