Read Bytes data from fetch response - arrays

Question

I want to convert an Android-Kotlin project to React Native, and I have a problem:
The Kotlin project handle data fetch from api like that:
import java.net.URL
import java.nio.ByteBuffer
import java.nio.ByteOrder
fun getData() {
val bytes = try {
URL(address).readBytes()
} catch (e: Exception) {
return emptySet()
}
val arrayBuffer = ByteBuffer
.wrap(bytes)
.order(ByteOrder.BIG_ENDIAN)
}
return arrayBuffer
}
fun URL.readBytes(settings: HeaderSetter? = null): ByteArray {
val request = Request.Builder()
.url(this).let {
settings?.invoke(it) ?: it
}.build()
return client.newCall(request).execute().also { if (it.code() != 200) throw IOException("CODE ${it.code()}") }.body()?.use { it.bytes() } ?: throw IOException()
}
var clientHolder: OkHttpClient? = null
val client: OkHttpClient
get() = clientHolder ?: clientBuilder.build().also {
clientHolder = it
}
How I do it in react-native ?

Answer 1

For people arriving from search engines and looking to get an answer to the question as written in the title, the way to read bytes from a fetch response is to use Response.arrayBuffer or Response.blob.
More information can be found here: https://developer.mozilla.org/en-US/docs/Web/API/Response
Some unsolicited tips for working with array buffers:
To access individual bytes use Uint8Array - i.e. new Uint8Array(array)
To view bytes as a (a.k.a primitive hexdump) decode them as iso-8859-1 using TextDecoder - i.e. new TextDecoder("iso-8859-1")
To convert bytes to normal strings, also use TextDecoder.