import fs from 'node:fs';
import getStream from 'get-stream';
import FirstChunkStream from 'first-chunk-stream';
import {uint8ArrayToString} from 'uint8array-extras';
// unicorn.txt => unicorn rainbow
const stream = fs.createReadStream('unicorn.txt')
	.pipe(new FirstChunkStream({chunkSize: 7}, async (chunk, encoding) => {
		return uint8ArrayToString(chunk).toUpperCase();
	}));
const data = await getStream(stream);
if (data.length < 7) {
	throw new Error('Couldn\'t get the minimum required first chunk length');
}
console.log(data);
//=> 'UNICORN rainbow'

import FirstChunkStream from 'first-chunk-stream';
new FirstChunkStream({chunkSize: 7}, async (chunk, encoding) => {
	return chunk; // Send buffer to stream
});
new FirstChunkStream({chunkSize: 7}, async (chunk, encoding) => {
	return {
		buffer: chunk,
		encoding: encoding,
	}; // Send buffer with encoding to stream
});
new FirstChunkStream({chunkSize: 7}, async (chunk, encoding) => {
	return FirstChunkStream.stop; // End the stream early
});
new FirstChunkStream({chunkSize: 7}, async (chunk, encoding) => {
	throw new Error('Unconditional error'); // Emit stream error
});