Any hints as to how to convert a Node `Buffer` to...

# javascript

[Didier Villevalois]

Any hints as to how to convert a Node Buffer to a Kotlin ByteArray, and vice-versa ?

[Tristan]

Not sure 🤔 What if you convert the Buffer into a String, and then use Kotlin's toByteArray function?

[Didier Villevalois]

Not sure whether that would be good if the Buffer contains binary data...

[Tristan]

Maybe you can do something like

val byteArray = listOf(*nodeBuffer).toByteArray()

[Didier Villevalois]

@Tristan it doesn't type-check. :(

[Didier Villevalois]

After a little research, it seems that ByteArray is backed by a JavaScript Int8Array and that Buffer extends from UInt8Array. So the following did the trick:

import Buffer
import org.khronos.webgl.Int8Array
import org.khronos.webgl.Uint8Array

fun ByteArray.toBuffer(): Buffer {
    val int8Array: Int8Array = this.unsafeCast<Int8Array>()
    return Uint8Array(
        int8Array.buffer,
        int8Array.byteOffset,
        int8Array.byteLength
    ).unsafeCast<Buffer>()
}

fun Buffer.toByteArray(): ByteArray {
    val uint8Array: Uint8Array = this.unsafeCast<Uint8Array>()
    return Int8Array(
        uint8Array.buffer,
        uint8Array.byteOffset,
        uint8Array.byteLength
    ).unsafeCast<ByteArray>()
}