Transform ReadableStream to async iterator of lines

readLine.ts

async function* readLines(stream: ReadableStream<Uint8Array>) {
  const reader = stream.getReader();
  let buffer = ''

  try {
    while (true) {
      const { done, value } = await reader.read();

      if (value !== undefined) {
        buffer += new TextDecoder().decode(value)
      }

      if (done) {
        if (buffer.length > 0) {
          yield buffer
        }
        break
      }

      let newlineIdx = -1

      do {
        newlineIdx = buffer.indexOf('\n')
        if (newlineIdx !== -1) {
          yield buffer.slice(0, newlineIdx)
          buffer = buffer.slice(newlineIdx + 1)
        }
      } while (newlineIdx !== -1)
    }
  } finally {
    reader.releaseLock()
  }
}