anylogger-tutorial

Simple tutorial project demonstrating anylogger

Scenario

We want to use logging in our app, but not lock ourselves in to a specific logging library. For now we will use debug with anylogger so we can switch to another logging library later if we want.

Assignment

Write a bunch of log messages to the console using anylogger. Then test whether we can make the log messages show up in the console like they would with debug.

Prepare a project

To prepare a project, either

Create a project manually

First create an empty Node project and add dependencies:

mkdir my-project
cd my-project
npm init
npm install --save anylogger anylogger-debug debug

Then create a file named index.js and add this code:

require('anylogger-debug')
var log = require('anylogger')('tutorial')

console.info(
  'Welcome to the anylogger tutorial.\n' +
  'Below we are testing anylogger-debug. For output to show up,\n' +
  'set the environment variable DEBUG=*\n'
)

log('This message is logged at level log')
log('debug', 'This message is logged at level debug')
log('info', 'This message is logged at level info')
log.warn('This message is logged at level warn')
log('error', 'Unfortunately, debug does not support levels.')

Finally, add a start command to the scripts section in package.json:

"scripts": {
  "start": "node index.js"
}

Clone this project

Git clone this repo to your machine and run

npm install

Start it

Once you have prepared the project, you can start it using:

npm start

> anylogger-tutorial@0.5.0 start C:\ws\anylogger-tutorial
> node index.js

Welcome to the anylogger tutorial.
Below we are testing anylogger-debug. For output to show up,
set the environment variable DEBUG=*

That's it! For now. This tutorial project uses anylogger-debug to make all calls to anylogger objects use debug below the hood.

So why don't we see anything?

debug is opt-in; in order for logging to show up, you need to enable it first:

set DEBUG=*

The asterisk here is a wildcard, matching all module names. This is actually all normal configuration for debug and not related to anylogger at all.

Now let's run it again:

npm start

> anylogger-tutorial@0.1.0 start C:\ws\anylogger-tutorial
> node index.js

Welcome to the anylogger tutorial.
Below we are testing anylogger-debug. For output to show up,
set the environment variable DEBUG=*

  tutorial This message is logged at level log +0ms
  tutorial This message is logged at level debug +0ms
  tutorial This message is logged at level info +0ms
  tutorial This message is logged at level warn +0ms
  tutorial Unfortunately, debug does not support levels. +1ms

And yes, our debug messages are showing up, in the format we know and love from debug.