stream on sliced Bunfile doesn't work

[bogeychan]

What version of Bun is running?

1.0.11

What platform is your computer?

No response

What steps can reproduce the bug?

Create the following files

./file.txt

12345

./index.ts

const file = Bun.file('./file.txt').slice(0, 2);

const content = await(new Response(file.stream())).text();

console.log(content);
console.log(file.size);

Run

bun run index.ts

What is the expected behavior?

Console output:

12
2

What do you see instead?

Console output:

12345
2

Additional information

No response

[veera-sivarajan]

Hi, I'd like to work on this.

[botxboom]

Hi @bogeychan , I was going through the read-file docs(https://bun.sh/guides/read-file/string) and found Bun.File() returns a file instance as :
FileRef ("./file.txt") { type: "text/plain;charset=utf-8" }

and you are performing slice on this instance. which won't slice the text inside the file.

To achieve that you can do:

const content = await(new Response(file.stream())).text();
console.log(content.slice(0,2))

You can also do:
const file = Bun.file(path);
const content = await file.text();

[veera-sivarajan]

From the docs (https://bun.sh/guides/read-file/string):

The Bun.file() function accepts a path and returns a BunFile instance. The BunFile class extends Blob and allows you to lazily read the file in a variety of formats.

And slice() is a method on Blob (https://developer.mozilla.org/en-US/docs/Web/API/Blob). So I think Bun.file('./file.txt').slice(0, 2); should work as expected?

I'm not sure though.

[anderspitman]

Given this bug, and the lack of node fs.createReadStream, is there currently a way to seek and stream chunks from a large file in Bun? It's not time critical for me, but my code supports Node and Deno, and would like it to support Bun eventually.