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kotlinlang

I don't remember anymore what's the best/right way to convert a Node.js `Buffer` to a Kotlin `ByteArray`

I guess `buffer._asList_()._toByteArray_()`, but I have no idea actually. :slightly_smiling_face:

I'd expect `.unsafeCast&lt;ByteArray&gt;()` to work, but actually since `Buffer` extends `UInt8Array` and not `Int8Array` it might have weird behavior without wrapping… haven't tested

(e.g. `Int8Array(buffer).unsafeCast&lt;ByteArray&gt;()`)

Draft (<https://gist.github.com/MikkoH/f8c5148871bb3ba57455|from gist>)
```val uint8 = Uint8Array(arrayOf(1,2))

// conversion
val int8 = Int8Array(uint8.buffer)
val ba = int8.asByteArray()```
`asByteArray()` extension - fine PR :)

<@U33H6SB2B> depends if the byte representation changes with
```Int8Array(uint8.buffer)```
Would `asByteArray` simply `unsafeCast`?

&gt; Would `asByteArray` simply `unsafeCast`?
Yes

Byte representation seems to remain the same.
So it would be a matter of adding `asByteArray`

`Uint8ClampedArray` will clamp values outside of range, as its name implies, other JS TypedArray types will reinterpret the bits

&gt; will reinterpret the bits
As a "view" over those bits tho, right?
If you transform a `Int8Array` to a `UInt8Array` you get back the correct result

yes, and ditto if you go through `Int32Array` etc. too (assuming you have a correct multiple number of bytes)

Btw. is there anything bad with my suggestion?

<@U0152P3VB5J> I guess I don't really like the additional `buffer._asList_()`

`.toByteArray` makes a copy while the `*TypedArray` constructors and `unsafeCast` don't

Well, apart from the copying every single byte

whether that matters is situational of course, but if you're using `Buffer` to begin with…

<@U010G5DQZPW> What is your use case?
Do you need `ByteArray` for Kotlin library?

cc <@U024KPT8ZUL>

<@U33H6SB2B> sorry didn't get pinged. I need to expose a `ByteArray` in common code, thus I need to convert the JS `Buffer` to said `ByteArray`