Allow to specify ranges for partial loading

[Fuzzyma]

Sometimes it might be useful to load only parts of a file. Hence it might be useful to allow for ranges to be specified.

Something along the lines of:

import bytes from "./photo.png" with { type: "bytes", range: { from: 0, to: 500 } };

or

import bytes from "./photo.png" with { type: "bytes", offset: 500, length: 1000 };

or

import bytes from "./photo.png" with { type: "bytes", slice: [500, 1000] };

The Browser would then load the file via a range request.
Some servers might now support this. In that case, they usually just send the whole file which is a reasonable fallback in most cases but could lead to huge load times for scripts in this case. So not sure how to handle that...

[bakkot]

I have a hard time imagining use cases for this. Can you give some examples?

[Fuzzyma]

I am thinking about import of larger binary files were you sometimes only need a portion or the headers.

e.g. for models

import header from './model.glb' with {
  type: 'bytes',
  slice: [0, 20]
}

or or for texture packs

import playerSprite from './sprites.pack' with {
  type: 'bytes',
  slice: [offset, length]
}

or just some binary

import tiles from './rom.bin' with {
  type: 'bytes',
  slice: [0x8000, 0x2000]
}

Some things that are now a virtual module or vite plugin could potentially move to this syntax.

[styfle]

Sounds like it could be useful.

• JS engines in browsers could perform a range request
• JS engines in servers could read from the offset
• JS bundlers could avoid including the entire file and only include the partial content

That said, I don't think this needs to be part of the original proposal. It could be a new proposal on top so that we don't block progress on this proposal.