Encoding an avsc message with a Confluent spec header

encode.js

const magicByte = 0

// Optimized to try and not have to re-allocate memory through Buffer.concat. 
// We allocate 1k to begin with, hoping that fits the message
// and we don't have to relocate again. Otherwise, tough luck.
function toBuffer(value, type, schemaId, length = 1024) {
	const buf = Buffer.allocUnsafe(length) // unsafe, might contain old / sensitive data
	buf.writeInt8(magicByte)
	buf.writeInt32BE(schemaId, 1)

	const pos = type.encode(value, buf, 5)
	
	if (pos < 0) {
		// the buffer wasn't big enough, we'll have to try again
		return toBuffer(value, type, schemaId, length - pos)
	} else {
		return buf.slice(0, pos)
	}

}