modernize lib/file.js and calculate downloaded correctly

[jimmywarting]

this fixes the calculation of .files[i].downloaded

[request-info]

👋 We would appreciate it if you could provide us with more information about this issue.

[welcome]

🙌 Thanks for opening this pull request! You're awesome.

[KayleePop]

LGTM

[KayleePop]

I think these parentheses make the code more readable.

[jimmywarting]

Hmm, standard didn't complain and it wasn't needed so i thought i could safely remove them

[KayleePop]

It's just a style thing. probably not important.

[DiegoRBaquero]

I'd rather keep them

[jimmywarting]

I also notice file.download is calculated wrong.

Using the Sintel torrent as an example...
https://instant.io/#08ada5a7a6183aae1e09d831df6748d566095a10
(this can be tested in the console)

It has 6 srt files and 1 small piece of the mp4 file in the first piece
after the first piece is downloaded you can see that the first files are complete but the progress and downloaded are incorrect

const file = client.get('08ada5a7a6183aae1e09d831df6748d566095a10').files[0]
console.log(file.done) // true
console.log(file.progress) // 39.58777239709443 <- incorrect b/c of download
console.log(file.downloaded) // 65399 <- this file fits inside one chunk and it's too big
console.log(file.length) // 1652

I'm working on did a fix for that now also

[KayleePop]

That should be a separate PR I think

[DiegoRBaquero]

Correct, please separate into two PRs, let's keep this one about modernizing the code.

[jimmywarting]

ok, closing this then, new pr: #1478