file-timestamp-stream

file-timestamp-stream

This module creates stream.Writable to a file which is automatically rotated based on current time and uses strftime template for file names.

Requirements

This module requires ES2021 with Node >= 16.

Installation

npm install file-timestamp-stream

Additionally for Typescript:

npm install -D @types/node

Usage

Example:

import FileTimestampStream from "file-timestamp-stream"
// or
import {FileTimestampStream} from "file-timestamp-stream"

Options

• flags is a string with flags for the opened stream (default: 'a')
• fs is a custom fs module (optional)
• path is a template for new filenames (default: 'out.log')

Example:

Basic path based on strftime parameters:

const stream = new FileTimestampStream({
  path: "%Y-%m-%dT%H.log",
  flags: "a",
})

newFilename

This method can be overridden in the subclass.

The method generates a filename for new files. By default, it returns a new filename based on path and current time.

Example:

import strftime from "ultra-strftime"

class MyFileTimestampStream extends FileTimestampStream {
  /** count how many files has been created */
  counter = 0

  // for pure Javascript explicit constructor is necessary
  // constructor (options) { super(options); this.counter = 0 }

  protected newFilename(): string {
    const filename = strftime(this.path)
    if (filename !== this.currentFilename) this.counter++
    return filename
  }
}

const stream = new MyFileTimestampStream({
  path: "%Y-%m-%dT%H:%M.log",
})

Properties

Readonly public properties based on contructor's options:

• flags
• fs
• path

Protected properties for a custom subclass:

• currentFilename contains the last opened filename
• stream contains current fs.WriteStream object

Path template format

A path can contain strftime specifiers.

Warning

This stream has to be closed to free streams and timers.

License

Copyright (c) 2017-2024 Piotr Roszatycki [e-mail]

MIT

Changelog

v3.0.0 2024-06-26

• Converted to ESM module.
• Requires Node >= 16.
• Uses timers-obj@3.
• Unref timers so they don't block the event loop.