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 several instances of debug such as namespace:info, namespace:warn, namespace:error, etc. All these are configurable. 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.trace("I'm a trace output");
log.debug("I'm a debug output");
log.log("I'm a log 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.debug.logger()("the debug instance of debug, using 'myapp:debug' namespace");
var debug = debugLogger.debug('myapp:visionmedia');
debug('Nothing tastes better than the original!');

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.colors.magenta;
debugLogger.levels.error.prefix = 'ERROR ';

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

Add log levels

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

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

Multiple arguments / util.format style

log.log("Multiple", "arguments", "including", "objects:", { obj: 'obj'}, "makes life easier");
log.warn("util.format style string: %s, number: %d and json: %j.", "foo", 13, { obj: 'json'});

Filter by 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, each level will have a specific color. 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 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

.config(obj)

Configures debug-logger. Returns debug-logger to allow chaining operations.

.debug

Returns visionmedia/debug module.