logor

© 2016, Onur Yıldırım (@onury). MIT License.

Simple logging utility with levels, for Node.js.
This also brings some nice formatting, colors and JSON capabilities to your logs.
npm i logor

Usage

var log = require('logor').config({
    level: 2, // log.Level.INFO
    colors: true,
    format: '{DATE} {TIME}  {LEVEL}\t{*}'
});
 
log.info('Output colorful logs with date/time and level info.');
 

Output Example

Log Levels and Methods

Level		Method	Color	Details
ERROR	0	.error()	Red	Error logs. Always output to the console.
WARN	1	.warn()	Yellow	Warning logs.
INFO	2	.info()	Cyan	Informational logs.
		.log()	None	Regardless the config, output has no colors, date/time or level info. Clean text.
		.json()	Cyan	Safely JSON stringifies the arguments. Handles circular references.
		.jsonf()	Cyan	Same as .json() method, but with formatting.
DEBUG	3	.debug()	Magenta	Debug logs.
		.trace()	None	Prints the message to stderr with stack trace to the current position in the code.
VERBOSE	4	.verbose()	Gray	Silly/verbose logs.

Configuration

Pass an options object to log.config() method, with the following properties:

Option	Type	Default	Description
level	Number	4	Logging level. Levels are prioritized from 0 to 4 (highest to lowest). See Log Levels.
colors	Boolean	true	Whether colors should be enabled.
format	String|Function	'{*}'	Format of the log output. Takes placeholders: DATE, TIME, LEVEL and *. See Formatting Output.

Set all options at once:

log.config({
    level: 2,
    colors: true,
    format: '{*}'
});

Set log level:

log.level = 2;
// When you set level to `2` (`INFO`),
// levels with greater values will not output any logs.
log.debug('This will not be logged.');

Enable/disable all colors:

log.colors = false;
log.info('Log without colors');
// —> Log without colors

Formatting Output

{} around a placeholder indicates that colors should be applied for that component. e.g. magenta if this is a debug log. Use () instead, to gray-out that component; or [] for no colors.

{color} » (gray) » [none]

Placeholder	Details
*	Actual argument(s) being logged. If omitted, it will be appended at the end.
DATE	Short ISO date.
TIME	Time in HH:mm:ss format.
LEVEL	Name of the current logging level.

Logs with date/time:

log.format = '{DATE} {TIME}\t{*}';
log.info('Log with full date/time');
// —> 2016-08-18 15:30:43   Log with full date/time

Logs with level info:

log.format = '{TIME}\t{LEVEL}\t{*}';
log.info('Log with time and level');
// —> 15:30:43   INFO    Log with time and level

log.format = '(TIME)\t{LEVEL}\t[*]';
log.info('This is the default color of the console.');
// —> 15:30:43   INFO   This is the default color of the console.

JSON Logs

Use log.json() to output a log with stringified argument(s).
Use log.jsonf() to also format with indents.
Use log.s() to stringify an individual or multiple values.
Use log.sf() to also format with indents.

This also handles circular references.

log.json({ info: 'this is an object' });
log.jsonf({ jsonf: 'this is a formatted json.' });
log.error(log.s({ 'stringify-arg': 'log.error(log.s(object))' }));
log.warn(log.sf({ 'stringify-format': 'log.warn(log.sf(object))' }));

Change-Log

v1.0.1 (2016-09-05)

• Return self from .config() method.

v1.0.0 (2016-08-20)

• initial release.

License

MIT.