To help you get started, we've collected the most common ways that tracer is being used within popular public projects.

tracer for node.js

A powerful and customizable logging library for node.js.

===========

Features

---

• print log messages with timestamp, file name, method name, line number, path or call stack
• be customized output format with micro-template and timestamp format
• support user-defined logging levels
• add easily any transport
• support filter functions, so print statements in full color and font (color console)

Install

---

npm install tracer --save

Usage

Add to your code:

Simple Console

var logger = require('tracer').console()

Color Console

var logger = require('tracer').colorConsole()

Set Output Level

var logger = require('tracer').colorConsole({ level: 'warn' })

Simple Example

Simple Console

var logger = require('tracer').console();

logger.log('hello');
logger.trace('hello', 'world');
logger.debug('hello %s',  'world', 123);
logger.info('hello %s %d',  'world', 123, {foo:'bar'});
logger.warn('hello %s %d %j', 'world', 123, {foo:'bar'});
logger.error('hello %s %d %j', 'world', 123, {foo:'bar'}, [1, 2, 3, 4], Object);

$ node example/console.js
2012-03-02T13:35:22.83Z  console.js:3 (Object.) hello
2012-03-02T13:35:22.85Z  console.js:4 (Object.) hello world
2012-03-02T13:35:22.85Z  console.js:5 (Object.) hello world 123
2012-03-02T13:35:22.85Z  console.js:6 (Object.) hello world 123 { foo: 'bar' }
2012-03-02T13:35:22.85Z  console.js:7 (Object.) hello world 123 {"foo":"bar"}
2012-03-02T13:35:22.85Z  console.js:8 (Object.) hello world 123 {"foo":"bar"} [ 1, 2, 3, 4 ] function Object() { [native code] }

Color Console

var logger = require('tracer').colorConsole()

logger.log('hello')
logger.trace('hello', 'world')
logger.debug('hello %s', 'world', 123)
logger.info('hello %s %d', 'world', 123, { foo: 'bar' })
logger.warn('hello %s %d %j', 'world', 123, { foo: 'bar' })
logger.error(
  'hello %s %d %j',
  'world',
  123,
  { foo: 'bar' },
  [1, 2, 3, 4],
  Object
)

Daily Log

var logger = require('tracer').dailyfile({
  root: '.',
  maxLogFiles: 10,
  allLogsFileName: 'myAppName'
})

logger.log('hello')
logger.trace('hello', 'world')
logger.debug('hello %s', 'world', 123)
logger.info('hello %s %d', 'world', 123, { foo: 'bar' })
logger.warn('hello %s %d %j', 'world', 123, { foo: 'bar' })
logger.error(
  'hello %s %d %j',
  'world',
  123,
  { foo: 'bar' },
  [1, 2, 3, 4],
  Object
)

> dailylog will output all types log to diff files every day like log4j and if we provide allLogsFileName then all logs > will be move to that file too.

Advanced Example

some helper package is need, so install -dev for running examples

npm install -dev tracer

Take a look at the examples directory for different examples.

Set logging level

the level option support index (number) or method name.

var logger = require('tracer').console({ level: 'warn' })

equal

var logger = require('tracer').console({ level: 4 })

var logger = require('tracer').console({ level: 'warn' })
logger.log('hello')
logger.trace('hello', 'world')
logger.debug('hello %s', 'world', 123)
logger.info('hello %s %d', 'world', 123, { foo: 'bar' })
logger.warn('hello %s %d %j', 'world', 123, { foo: 'bar' })
logger.error(
  'hello %s %d %j',
  'world',
  123,
  { foo: 'bar' },
  [1, 2, 3, 4],
  Object
)

//$ node example/level.js
//2012-03-02T13:41:33.29Z  level.js:6 (Object.) hello world 123 {"foo":"bar"}
//2012-03-02T13:41:33.30Z  level.js:7 (Object.) hello world 123 {"foo":"bar"} [ 1, 2, 3, 4 ] function Object() { [native code] }

//log,trace, debug and info level was not ouputed

Customize output format

format tag:

• timestamp: current time
• title: method name, default is 'log', 'trace', 'debug', 'info', 'warn', 'error','fatal'
• level: method level, default is 'log':0, 'trace':1, 'debug':2, 'info':3, 'warn':4, 'error':5, 'fatal':6
• message: printf message, support %s string, %d number, %j JSON and auto inspect
• file: file name
• line: line number
• pos: position
• path: file's path
• folder: file's parent folder
• method: method name of caller
• stack: call stack message

we use tinytim micro-template system to output log. see details tinytim. and, we use Date Format to format datetime.

var logger = require('tracer').console({
  format: '{{timestamp}} <{{title}}> {{message}} (in {{file}}:{{line}})',
  dateformat: 'HH:MM:ss.L'
})

Or, you can set special format for output method

var logger = require('tracer').colorConsole({
  format: [
    '{{timestamp}} <{{title}}> {{message}} (in {{file}}:{{line}})', //default format
    {
      error:
        '{{timestamp}} <{{title}}> {{message}} (in {{file}}:{{line}})\nCall Stack:\n{{stack}}' // error format
    }
  ],
  dateformat: 'HH:MM:ss.L',
  preprocess: function(data) {
    data.title = data.title.toUpperCase()
  }
})

the preprocess method is a choice for changing tag.

Customize output methods

var colors = require('colors')

var logger = require('tracer').colorConsole({
  level: 'log1',
  methods: ['log0', 'log1', 'log2', 'log3', 'log4', 'log5'],
  filters: [colors.underline, colors.yellow]
})
logger.log0('hello')
logger.log1('hello', 'world')
logger.log2('hello %s', 'world', 123)
logger.log4('hello %s %d', 'world', 123)
logger.log5('hello %s %d', 'world', 123)

Customize filters

each filtes function was called. the function is synchronous and must be like

function f1(str) {
  return str.toUpperCase()
}

About Colors.js

var colors = require('colors')
var logger = require('tracer').colorConsole({
  filters: [
    f1,
    colors.underline,
    colors.blue, //default filter
    //the last item can be custom filter. here is "warn" and "error" filter
    {
      warn: colors.yellow,
      error: [f1, colors.red, colors.bold]
    }
  ]
})

the filter support key-function pair, example: color_console.js

{
		filters : {
			//log : colors.black,
			trace : colors.magenta,
			debug : colors.blue,
			info : colors.green,
			warn : colors.yellow,
			error : [ colors.red, colors.bold ]
		}
}

and the filters is an array, the last item can be custom filter. see example:filter.js

Log File Transport

var fs = require('fs')

var logger = require('tracer').console({
  transport: function(data) {
    console.log(data.output)
    fs.appendFile('./file.log', data.rawoutput + '\n', err => {
      if (err) throw err
    })
  }
})

logger.log('hello')
logger.trace('hello', 'world')
logger.debug('hello %s', 'world', 123)
logger.info('hello %s %d', 'world', 123, { foo: 'bar' })
logger.warn('hello %s %d %j', 'world', 123, { foo: 'bar' })
logger.error(
  'hello %s %d %j',
  'world',
  123,
  { foo: 'bar' },
  [1, 2, 3, 4],
  Object
)

Stream Transport

var fs = require('fs')

var logger = require('tracer').console({
  transport: function(data) {
    console.log(data.output)
    var stream = fs
      .createWriteStream('./stream.log', {
        flags: 'a',
        encoding: 'utf8',
        mode: 0666
      })
      .write(data.rawoutput + '\n')
  }
})

logger.log('hello')
logger.trace('hello', 'world')
logger.debug('hello %s', 'world', 123)
logger.info('hello %s %d', 'world', 123, { foo: 'bar' })
logger.warn('hello %s %d %j', 'world', 123, { foo: 'bar' })
logger.error(
  'hello %s %d %j',
  'world',
  123,
  { foo: 'bar' },
  [1, 2, 3, 4],
  Object
)

MongoDB Transport

var mongo = require('mongoskin')
var db = mongo.db('127.0.0.1:27017/test?auto_reconnect')

var log_conf = {
  transport: function(data) {
    console.log(data.output)
    var loginfo = db.collection('loginfo')
    loginfo.insert(data, function(err, log) {
      if (err) {
        console.error(err)
      }
    })
  }
}

var logger = require('tracer').console(log_conf)

logger.log('hello')
logger.trace('hello', 'world')
logger.debug('hello %s', 'world', 123)
logger.info('hello %s %d', 'world', 123, { foo: 'bar' })
logger.warn('hello %s %d %j', 'world', 123, { foo: 'bar' })
logger.error(
  'hello %s %d %j',
  'world',
  123,
  { foo: 'bar' },
  [1, 2, 3, 4],
  Object
)

console.log('\n\n\npress ctrl-c to exit')

Defining Multiple Transport

var fs = require('fs');
var logger = require('tracer').console({
	transport: [
		function (data) {
			fs.appendFile('./file.log', data.rawoutput + '\n', (err) => {
				if (err) throw err;
			});
		},
		function(data) {
			console.log(data.output);
		}
	]
});
logger.log('hello');
logger.trace('hello', 'world');
logger.debug('hello %s', 'world', 123);
logger.info('hello %s %d', 'world', 123, {foo: 'bar'});
logger.warn('hello %s %d %j', 'world', 123, {foo: 'bar'});
logger.error('hello %s %d %j', 'world', 123, {foo: 'bar'}, [1, 2, 3, 4], Object);

Define your logging helper

the work is like color_console.js

var colors = require('colors')
module.exports = function(conf) {
  return require('./console')(
    {
      filters: {
        //log : colors.black,
        trace: colors.magenta,
        debug: colors.blue,
        info: colors.green,
        warn: colors.yellow,
        error: [colors.red, colors.bold]
      }
    },
    conf
  )
}

Customize output Object's properties

var obj = {
  Request: [
    {
      IsValid: ['True'],
      ItemSearchRequest: [
        {
          ResponseGroup: ['Small', 'OfferSummary'],
          Sort: ['salesrank'],
          SearchIndex: ['DVD']
        }
      ]
    }
  ]
}

var logger = require('tracer').console({
  inspectOpt: {
    showHidden: true, //the object's non-enumerable properties will be shown too
    depth: null //tells inspect how many times to recurse while formatting the object. This is useful for inspecting large complicated objects. Defaults to 2. To make it recurse indefinitely pass null.
  }
})
logger.log(obj)

//
// 2013-09-30T04:30:44.927Z  depth.js:26 (Object.) { Request:
//    [ { IsValid: [ 'True', [length]: 1 ],
//        ItemSearchRequest:
//         [ { ResponseGroup: [ 'Small', 'OfferSummary', [length]: 2 ],
//             Sort: [ 'salesrank', [length]: 1 ],
//             SearchIndex: [ 'DVD', [length]: 1 ] },
//           [length]: 1 ] },
//      [length]: 1 ] }

Specify the stack index for file info

Fix file, path, and line info width stackIndex. It is userful for development package.

var logger = require('tracer').console({
  stackIndex: 0 // default 0
})
var logger2 = require('tracer').console({
  stackIndex: 1
})
var logMgr = function(type, msg) {
  return logger[type](msg)
}
var logMgr2 = function(type, msg) {
  return logger2[type](msg)
}

logger.log('hello') // the line info is right
logger2.log('hello') // the line info is error
logMgr('log', 'hello') // the line info is error
logMgr2('log', 'hello') // the line info is right

setLevel and close

setLevel and close methods to dynamically change the log level. these are global settings, affect all output that are created via tracer

var tracer = require('tracer')
tracer.setLevel(2) //or tracer.setLevel('debug');
//... ...
tracer.close()

notice: if you set level in initialize, you can't change more lower level than the initial level.

var tracer = require('tracer')
var logger = tracer.console({ level: 'warn' })

logger.log('hello') //nothing output

tracer.setLevel(0) //dont work.
logger.log('hello') //nothing output

tracer.setLevel('error') //it works.
logger.warn('hello') //nothing output

logger.error('hello') //'hello'

Read examples please. setLevel.js

support console methods

support count, assert and table methods. Read examples please. consoleMethods.js

More features, please read examples.

History

1.3.0

• Update packages
• Enable dailyfile only on nodejs

1.1.6

• Merged: Typings for new methods #131 by @zS1L3NT
• Merged: Update type of depth property in inspectOpt #134 by @SufianBabri

1.1.5

• Updated some packages to the latest version. Fixed severity vulnerability

1.1.4

• Fixed fixes security vulnerability by GitHub bot
• Merged fix bug then when set allLogFile cannot delete old old files #122. Thanks @horsefaced
• Congratulations 1.1K Stargazers

1.1.0

• Updated map tracer.warn to console.warn. Thanks @eouia
• Fixed webpack warning "Critical dependency: the request of a dependency is an expression". Thanks @tjr
• Fixed Move nyc from dependencies to devDependencies. Thanks @madarche

1.0.3

• Updated some packages to the latest version. Fixed severity vulnerability

1.0.2

• Updated some packages to the latest version
• Released

0.9.9

• Fixed. Port tests from expresso to mocha. Fixes #105 #106 by @ossdev07.
• Fixed. Update type definitions to be able to use array in filters. #104 by @irisked.
• Fixed potential security vulnerabilities in your dependencies in istanbul package.

0.9.8

• Added. {{folder}} template option for parent folder. #96 by @shbatm.
• Added. rootDir param option for folder. #99 by @nswbmw. sample: folder.js and folder2.js

0.9.5

• Fixed. Update index.d.ts and dtslint for typescript. #92 and #94 by @Diluka.

0.9.3

• Fixed. Any custom keys for typescript. #90 by @Diluka.
• Updated formatJson sample

0.9.2

• Fixed. Make type definitions correct & add comments. #89 by @plylrnsdy.
• Updated npm packages

0.9.1

• Fixed. transport function parameter data type is LogOutput not string #87 by @myfjdthink.

0.9.0

• Added support all console methods, include count,assert and table. a new option 'supportConsoleMethods' is true default. example: consoleMethods.js in example folder.

0.8.15

• Adding type definitions #84 by @kobim
• Added data.rawoutput #83 by @Royalgamer06
• recommended linting #82 by @elomariAchraf

0.8.12

• added the ability to load the config from a file. #80 thanks @muthursyamburi
• fix a bug for windows cant create dailyfile dir #77 by @moonrailgun
• fixed. no fatal color in colorConsole missed. #79

0.8.11

• added fatal level, like log4j. #75 thanks @ds3783
• fixed double-log file issue. #71 thanks @huangts
• and something missed

0.8.4-0.8.7

• added some codes, details: #56 thanks @AmitThakkar

0.8.3

• fixed: Got extra data in the log file. #45 thanks @JohnSmithDr
• merged: Add Strict mode and EsLint from @HakmiSofian
• merged: Change the log to file example to using fs.appendFile() instead. from @twang2218
• merged: Enable use of tracer in strict mode from @madarche
• merged: Added getter for log level from @ColRad
• tested on node.js 4/5

0.8.2

• added: Defining a field for max file days filea. #35 thanks @AmitThakkar

0.8.1

• added: Adding support for Multiple Transports. #36 thanks @AmitThakkar
• fixed: dailyfile auto create folder #37. thanks @klesh

0.8.0

• added: setLevel method to dynamically change the log level. thanks @madarche, #30
• added: close method to end all of the writable streams. thanks @loht, #31

0.7.4

• fixed: use the lastest package of colors v1.0.3.
• fixed: removed filter's second parameter

0.7.3

• restored: use colors package replace cli-color, because some bugs and a lot of dependencies in cli-color. ref colorConsole2.js example.

0.7.2

• fixed: change log dateformat from UTC to LOCAL iso format (Suggest by @felixhao28)
• fixed: change color package from colors to cli-color (Suggest by @jeffreydwalter)

0.7.1

• added: format add %j placeholder (Thanks @Bacra)
• added: add stackIndex opt to specify the index of stack (Thanks @Bacra)

0.7.0

• fixed: change inspect format, using new format of node.js 0.10. (Thanks @Bacra)
• fixed: now support node.js 0.10 and above, NO Support 0.8 and 0.6

0.6.2

• fixed: change stack from array to string, and fixed example2.js

0.6.1

• fixed: get the filename correctly on windows. thanks Tom Carchrae
• added: added missing repository field. thanks @madarche

0.6.0

• feature: add showHidden and depth option for showing object's properties.

0.5.1

• feature: add args into data object, now we can check args in preprocess, see example format2.js, merge from yasuyk04/work

0.5.0

• performance: speed up when the format don't include method,path,line,pos,file, thanks sharonjl's issue report

0.4.2

• fixed: debug color from blue to cyan

0.4.1

• fixed: default timestamp is ISO UTC format.

0.4.0

• feature: support dailyfile method, added some examples
• feature: add preprocess custom method for changing tags before format

0.3.5

• fixed bug: can't get method/line number in express

0.3.4

• use tinytim package

0.3.3

• spell missing (transpot->transport)

0.3.2

• speed-up for _log function
• add some test codes

0.3.1

• minor-fix for call stack

0.3.0

• support custom format and filter for special method

0.2.1

• fix spell missing

0.2.0

• Add more examples.
• Default methods is log, trace, debug, info, warn, error.
• Support 'string' level, {level:'warn'} equal {level:4}

0.1.0

• Initial Tracer implementation.

License

(The MIT License)

Copyright (c) 2012 LI Long <lilong@gmail.com>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.