debug-logger

debug-logger

A thin wrapper for visionmedia/debug logger, adding levels and colored output.

Overview

visionmedia/debug is a ubitiquous logging library with 1000+ dependants. Given how widespread it is and the convenience of namespaces it is a great logger for library modules. debug-logger is a convenience wrapper around debug that adds level based coloured output. Each instance of debug-logger will lazily instantiate 3 instances of debug, one for general purpose logging using namespace, another for debug (namespace:debug) and another for trace (namespace:trace). All this in configurable fashion. debug-logger has no dependencies besides debug.

At AppsCot we use debug-logger in waterline-orientdb.

Instalation

npm install debug-logger -S

Usage

var log = require('debug-logger')('myapp');

log.debug("I'm a debug output");
log.info("I'm an info output");
log.warn("I'm a warn output");
log.error("I'm an error output");

Inspect error/object

var err = new Error('error message');
err.stack = 'the stack\nline2\nline3';

log.error('Something failed:', err);

var obj = {
  anumber : 1234,
  astring : 'str',
  adate : new Date(),
  aboolean : true
};
log.info("let's inspect 'obj'", obj);

Original debug instances and enabled property

log.info.logger()("the default instance of debug, using 'myapp' namespace");
log.debug.logger()("the debug instance of debug, using 'myapp:debug' namespace");

if (log.debug.enabled()) {
  // This only runs if environment variable DEBUG includes "myapp:debug" namespace
  log.debug("Debug is enabled");
}

util.inspect options

Full util.inspect options available at nodejs.org.

var debugLogger = require('debug-logger');
debugLogger.inspectOptions = {
  colors : true
};
log.info('By enabling colors we get this nice colored example:', {
  anumber : 1234,
  astring : 'str',
  adate : new Date(),
  aboolean : true
});

Customize available log levels

debugLogger.levels.error.color = debugLogger.getForeColor('magenta');
debugLogger.levels.debug.color = debugLogger.getBackColor('cyan') + debugLogger.getForeColor('white');

var customColorLog = debugLogger('myapp');
customColorLog.error("I'm a 'magenta' error output");
customColorLog.debug("I'm a 'cyan'/'white' debug output");

Add log levels

debugLogger.levels.silly = {
  color : debugLogger.getForeColor('magenta'),
  prefix : 'SILLY  ',
  namespaceSuffix : ':silly'
};

var sillyLog = debugLogger('myapp');
sillyLog.silly("I'm a silly output");

Filter log level (instead of namespace)

export DEBUG_LEVEL=info

Only info level and above logs will be outputted.

More examples in the examples folder.

Reference

Instance Methods

Assuming log is an instance of debug-logger (var log = require('debug-logger')('myapp');).

log.trace([data][, ...])

log.debug([data][, ...])

log.log([data][, ...])

log.info([data][, ...])

log.warn([data][, ...])

log.error([data][, ...])

Prints the data prepended by log level. If the terminal supports colors, the level will be one of: blue, green, yellow, red. If an Error is provided, the toString() and call stack will be outputted. If an Object is provided the toString() and util.inspect() will be outputted. Example:

  myapp:debug DEBUG  I'm a debug output +0ms
  myapp       INFO   I'm an info output +1ms

This function can take multiple arguments in a printf()-like way, if formatting elements are not found in the first string then util.inspect is used on each argument.

log[level].logger()

Returns the default debug instance used by level.

log[level].enabled()

Boolean indicating if level's logger is enabled.

Module

.getForeColor(color)

Returns an ANSI foreground color code string. color is one of black, red, green, yellow, blue, magenta, cyan, white Example:

  debugLogger.getForeColor('cyan')
  // returns '\x1b[36m'

.getBackColor(color)

Returns an ANSI background color code string.

.debug

Returns visionmedia/debug module.