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

Building

To build the code and run the tests:

$ npm install
$ npm run build

Contributing

Contributions are welcome! Please see CONTRIBUTING.md.

License

MIT - see LICENSE.md