# polog
> very fast and simple console logging library
Latest version **1.2.4** (published 2018-03-22) · MIT license · 0 weekly downloads
## Install
```sh
npm install polog
pnpm add polog
yarn add polog
bun add polog
```
## Health
**Score 15/100 (F)** — status: abandoned.
Positive: no vulnerabilities.
Warnings: low downloads; no types; no esm support.
Negative: abandoned; low maintenance score.
## Facts
| | |
|---|---|
| Version | 1.2.4 |
| Published | 2018-03-22 |
| First published | 2017-05-03 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | none |
| Module format | CommonJS |
| Dependencies | 0 |
| Unpacked size | 9.2 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| Author | Petar Koretic |
| Maintainers | pkoretic |
## Links
- npm: https://www.npmjs.com/package/polog
- npm.io page: https://npm.io/package/polog
## Recent versions
- 1.2.4 (latest) — 2018-03-22
- 1.2.3 — 2018-02-05
- 1.2.2 — 2017-11-25
- 1.2.1 — 2017-05-16
- 1.2.0 — 2017-05-10
- 1.1.3 — 2017-05-07
- 1.1.2 — 2017-05-07
- 1.1.1 — 2017-05-07
- 1.1.0 — 2017-05-07
- 1.0.2 — 2017-05-06
- 1.0.1 — 2017-05-05
- 1.0.0 — 2017-05-05
- 0.9.0 — 2017-05-03
## README
[](https://github.com/pkoretic/polog/blob/master/LICENSE)
[](https://www.npmjs.com/package/polog)
`polog` is one of the [fastest](benchmarks) and simplest Node.js logging libraries that behaves as the
standard `console` command. It has no dependencies and adds minor features as timestamp, log levels
and json as opt-in. This library uses as little processing power as possible to avoid affecting
Node.js event loop.
Logging (in Node.js) should always use stdout/stderr and leave advanced logging manipulation to the
rest of the stack. For best performance and asynchronous operation you should use pipes on Linux as
mentioned in [official docs](https://nodejs.org/api/process.html#process_a_note_on_process_i_o).
This also enables you to do file logging as efficiently as possible.
`console` uses process.stdout.write which has the same behaviour as this library.
## Installation
```
npm install polog
```
## Options
Options can be passed as object before creation.
**debug** - `true/false` - enable output of `.debug` function, if set to `false` (default) it won't print anything
```
const log = require("polog")({ debug: true })
log.debug("will be shown")
```
**format** - `true/false` - enable usage of util.format, ie:
```
const log = require("polog")({ format: true })
log.info("test: %d", Math.random())
```
if set to `false` (default), which is faster, use ES6 template strings
```
log.info("test: ${Math.random()}")
```
**prefix** - `function` - prefix messages with custom output, default is `Date.now`
```
const log = require("../index.js")({ prefix: () => { return (new Date).toISOString() }})
```
Keep in mind that this is also called on every message output, so you want to keep it as simple as
possible.
**json** - `true/false` - use json array format, defaults to `false`
```
const log = require("polog")({ json: true })
log.info("json")
```
## Levels and properties
There are four standard levels:
**info** `I` - standard `stdout` output
**debug** `D` - debug `stdout` output, depens on `debug` options, useful for (NON)PRODUCTION
environment switching
**warn** `W` - `stderr` warnings output
**error** `E` - `stderr` error output
Currently there is no way to add new levels, if that is wanted, please open an issue.
**debugMode** - `true/false` contains information if debug level is enabled or not
**enableDebug()** - enable debug - same as `debug: true` option at creation time
**disableDebug()** - disable debug - same as `debug: false (default)` option at creation time
## Standard logging
```
const log = require("polog")({ debug: true })
log.debug("debug mode") // shown only when debug is set to true above
log.info("hello there!")
log.warn("be careful")
log.error("not good")
```
This will output:
```
1494005876469 D debug mode
1494005876469 I hello there!
1494005876470 W be careful
1494005876470 E not good
```
Using `format` option:
```
const log = require("polog")({ format: true })
log.info("test message: %d", Math.random())
```
outputs:
```
// # 1494006079148 I test message: 0.17100814691155053
```
This calls [util.format](https://nodejs.org/api/util.html#util_util_format_format_args) that is also
used by `console.*` functions. It is slower since every message has to be processed first. It is
recommended to use ES6 template string instead:
```
const log = require("polog")()
log.info(`test message: ${Math.random()}`)
````
Changing `prefix`:
```
const log = require("../index.js")({ prefix: () => { return (new Date).toISOString() }})
log.info("test message")
```
outputs:
```
2017-05-05T17:53:05.702Z I test message
```
This is probably more user friendly, although default `Date.now` is faster since Date object doesn't
have to be created for every function call.
Using `json`:
```
const log = require("../index.js")({ json: true })
log.info("test message")
```
outputs:
```
[1494153657008,"I","json!"]
```
## Fast file logging on Linux
Redirect (pipe) all logs to a file [asynchronously](https://nodejs.org/api/process.html#process_a_note_on_process_i_o)
```
node app.js > app.log 2>&1
```
Split standard and error logs
```
node app.js > access.log 2>error.log
```
## Disabling logs
Sometimes it might be useful to disable logging library from the outside, like when testing. This
can be done setting `NOLOG` env variable to `true`.
```
NOLOG=true node examples/format.js
```
In this case no logs are shown.
## [Benchmarks](benchmarks)
This should be the fastest logging library for Node.js as far as we know. [Test](benchmarks) it
yourself and provide feedback.
## Support
* Issues - [open new issue](https://github.com/pkoretic/polog/issues)
* mail - petar.koretic@gmail.com
* IRC - `pkoretic` on freenode
## Changelog
**1.1.0** Adds `json` support.
**1.0.0** Initial release
---
_Source: https://npm.io/package/polog · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._
