Logarama NPM | npm.io

logarama

Yet another simple logging library for the browser with minimum levels and hierarchical loggers.

All log methods map to same-named console methods.
An instantiate-able Logger class - allowing for multiple separate logger instances which can be individually controlled.
Create child loggers which inherit parent loggers' options and yet can be customized.
Change logging level (and children's logging levels) at runtime.
Override-able message formatting and output targets.
Supports UMD for easy integration within your project.
Small (<1KB).

Installation

$ npm install logarama

## How to use

var Logger = require('logarama');

var logger = new Logger();

logger.debug('this', 'is', 'an', 'array', [1,2,3]);

/*
[DEBUG]: this
[DEBUG]: is
[DEBUG]: an
[DEBUG]: array
[DEBUG]: [ 1, 2, 3 ]
*/

By default the minimum logging level is debug. You can override this:

var logger = new Logger({
  minLevel: 'error'
});

logger.trace(1);
logger.debug(2);
logger.info(3);
logger.warn(4);
logger.error(5);

/*
app[ERROR]: 5
*/

Change logging level at runtime:

var logger = new Logger({
  minLevel: 'error'
});

console.log(logger.minLevel()) /* error */

logger.debug(2);

logger.setMinLevel('debug');

console.log(logger.minLevel()) /* debug */

logger.debug(3);

/*
app[DEBUG]: 3
*/

Tags

Add a tag (prefix) to your messages:

var logger = new Logger('app');

logger.trace(1);
logger.debug(2);
logger.info(3);
logger.warn(4);
logger.error(5);

/*
app[TRACE]: 1
   (anonymous function) ...
app[DEBUG]: 2
app[INFO]: 3
app[WARN]: 4
app[ERROR]: 5
*/

The .throw() method is provided as a convient way of throwing an Error with the tag as a prefix:

var logger = new Logger('app');

// same as: throw new Error('(app) an error occurred')
logger.throw('an error occurred');

Formatting

You can override the built-in argument formatter with your own:

var logger = new Logger({
  format: function(arg) {
    return '{' + arg + '}';
  }
});

logger.debug(2, null, undefined, false, 'str', 23.2, [1,2,3]);

/*
app[DEBUG]: {2} {null} {undefined} {false} {str} {23.2} {1,2,3}
*/

Output targets

The default output target is the console. You can override this with your own:

var logMessagesToSend = [];

var logger = new Logger('Routing', {
  output: function(level, tag, msg) {
    logMessagesToSend.push([level, tag, msg])
  }
});

logger.debug(2, 3);
logger.warn('test')

console.log(logMessagesToSend);
/*
[
  ['debug', 'Routing', ['2', '3']],
  ['warn', 'Routing', 'test'],
]
*/

Child loggers

Child loggers inherit their parent's properties.

var logger = new Logger('parent', {
  minLevel: 'info',
});

var child = logger.create();
child.debug(2);
child.info(2);

/*
parent[INFO]: 2
*/

However, child tags are prefixed by their parents' tags:

var logger = new Logger('parent', {
  minLevel: 'info',
});

var child = logger.create('child');

child.info(2);

/*
parent/child[INFO]: 2
*/

Parent level changes get propagated down to children:

var logger = new Logger('parent', {
  minLevel: 'warn',
});

var child = logger.create('child', {
  minLevel: 'error',
});

child.info(2);
logger.setMinLevel('info');
child.info(3);

/*
parent/child[INFO]: 3
*/

Browser noConflict

If you're not using a module loader in browser environments then window.Logger gets set. You can use noConflict() to restore the original value of this property:

window.Logger = 2;

// load logarama.js
// window.Logger now equals the Logger class

// restore the original
var Logger = window.Logger.noConflict();

// window.Logger now equals 2