Writers

addWriter

function addWriter(writer: (formatted: string, level: string) => void): () => void

Subscribe to all formatted log output. Returns an unsubscribe function.

const lines: string[] = []
const unsub = addWriter((formatted, level) => {
  lines.push(formatted)
})

// Later:
unsub()

Writers receive output regardless of setOutputMode() or setSuppressConsole() settings.

createFileWriter

function createFileWriter(path: string, options?: FileWriterOptions): FileWriter

Create a buffered file writer that flushes automatically.

Options

Option	Type	Default	Description
bufferSize	number	4096	Flush when buffer exceeds this (bytes)
flushInterval	number	100	Flush every N milliseconds

FileWriter Methods

Method	Description
write(line)	Append line to buffer (adds \n)
flush()	Write buffer to disk immediately
close()	Flush remaining buffer and close file

Example

import { createFileWriter, addWriter } from "loggily"

const writer = createFileWriter("/tmp/app.log", {
  bufferSize: 8192,
  flushInterval: 200,
})

const unsub = addWriter((formatted) => writer.write(formatted))

// On shutdown:
unsub()
writer.close()

Safety

• The flush interval timer is unref()'d so it won't keep the process alive
• A process.on("exit") handler flushes remaining buffer on shutdown
• close() removes the exit handler and clears the interval
• Multiple close() calls are safe (idempotent)
• write() after close() is silently ignored