Console-stamp 3

This module lets you take control over the output from console logging methods in Node.js. Such as prefixing the log statement with timestamp information, log levels, add coloured output and much more.

Usage

Install

npm install console-stamp

Patching the console

You need to provide the console object to console-stamp in order to patch the builtin console.

require( 'console-stamp' )( console );

console.log('Hello, World!');

The default behaviour is to add a prefix to each log statement with timestamp information and log level.

[10.02.2019 15:37:43.452] [LOG]   Hello, World!

You can change this by provinding an options object as the second parameter.

require('console-stamp')(console, { 
    format: ':date(yyyy/mm/dd HH:MM:ss.l)' 
} );

console.log('Hello, World!');

[2020/01/19 13:56:49.383] Hello, World!

Notice how the log level is suddenly missing. You need to add it specifically to the format string.

require('console-stamp')(console, { 
    format: ':date(yyyy/mm/dd HH:MM:ss.l) :label' 
} );

console.log('Hello, World!');

[2020/01/19 23:20:30.371] [LOG] Hello, World!

Read more about how to customize the formatting of the log statement below.

Patch your own console

You can also provide a custom console with its own stdout and stderr like this:

const fs = require('fs');
const output = fs.createWriteStream('./stdout.log');
const errorOutput = fs.createWriteStream('./stderr.log');
const logger = new console.Console(output, errorOutput);

require('console-stamp')(logger, {
    stdout: output,
    stderr: errorOutput
});

Everything is then written to the files.

NOTE: If stderr isn't passed, warning and error output will be sent to the given stdout.

Backwards incompatibility with 2.x versions

console-stamp v3 has been rewritten adding tokens as a new and easier way to customize and extend your logging output.

With that in mind, some consessions has been made and you will probably need to update your console-stamp integration.

options.pattern is replaced by options.format

options.format is now the place where you provide the format of the logging prefix using tokens.

For example, { pattern: 'dd.mm.yyyy HH:MM:ss.l'} is replaced by { format: ':date(dd.mm.yyyy HH:MM:ss.l)' }.

PS: Providing a string with a date format based on dateformat as a second parameter is still supported.

options.label is gone

The log level label (INFO, DEBUG etc.) is now only shown if the token :label is part of the format string in options.format. It is part of the default format.

options.labelSuffix and options.labelPrefix are also gone as now you can provide these values directly in the options.format string.

Configuration

Here are some examples on how to customize your log statements with console-stamp.

Only update timestamp format

Without any other customizations you can provide the timestamp format directly.

require('console-stamp')( console, 'yyyy/mm/dd HH:MM:ss.l' );

To set the timestamp format using the options object you can use the date token.

require('console-stamp')(console, { 
    format: ':date(yyyy/mm/dd HH:MM:ss.l)' 
} );

console.log('Hello, World!');

[2020/01/19 23:08:39.202] Hello, World!

Add coloured output

console-stamp uses the excellent chalk library to provide coloured output and other styling.

require( 'console-stamp' )( console, {
    format: ':date().blue.bgWhite.underline :label(7)'
} );

You can also simply place some text in parenthesis, and then add your styling to that.

require( 'console-stamp' )( console, {
    format: '(->).yellow :date().blue.bgWhite.underline :label(7)'
} );

Note that by sending the parameter --no-color when you start your node app, will prevent any colors from console.

$ node my-app.js --no-color

For more examples on styling, check out the chalk documentation.

Tokens

There are only three predefined tokens registered by default. These are:

:date([format][,utc])[.color]
:label([padding])[.color]
:msg[.color]

:date([format][,utc])

• format {String}
  Containing the date format based on dateformat
  Default: 'dd.mm.yyyy HH:MM:ss.l'
• utc {Boolean}
  Set to true will return UTC-time
  Default: false

:label([padding])

• padding {Number}
  The total length of the label, including the brackets and padding
  Default: 7

:msg

• If the :msg token is provided in format, the output from the console will be returned in its place, otherwise the console output will be added as the last output, with no formatting.

Create a custom token

To define your own token, simply add a callback function with the token name to the tokens option. This callback function is expected to return a string. The value returned is then available as ":foo()" in this case:

require( 'console-stamp' )( console, {
    format: ':foo() :label(7)',
    tokens:{
        foo: () => {
            return '[my prefix]';
        }
    }
} );

console.log("Bar");

[my prefix] [LOG]   Bar

The token callback function is called with one argument, representing an Object with the following properties:

• method {String}
  The invoked method
• msg {String}
  The console output as a string
• params {Array}
  The token parameters (ex: The token call :label(7) will have params [7])
• tokens {Object}
  All the defined tokens, incl. the defaults
• defaultTokens {Object}
  Only the default tokens, even if it's been redefined in options

Example

Here we are making a custom date token called mydate using moment.js to format the date

const moment = require('moment');
moment.locale('ja');

require( 'console-stamp' )( console, {
    format: ':mydate() :label(7)',
    tokens:{
        mydate: () => {
            return `[${moment().format('LLLL')}]`;
        }
    }
} );

console.log('This is a console.log message');
console.info('This is a console.info message');
console.debug('This is a console.debug message');
console.warn('This is a console.warn message');
console.error('This is a console.error message');

Result:

[2016年5月12日午前11時10分 木曜日] [LOG]   This is a console.log message
[2016年5月12日午前11時10分 木曜日] [INFO]  This is a console.info message
[2016年5月12日午前11時10分 木曜日] [DEBUG] This is a console.debug message
[2016年5月12日午前11時10分 木曜日] [WARN]  This is a console.warn message
[2016年5月12日午前11時10分 木曜日] [ERROR] This is a console.error message

Custom Methods

The option.extend option enables the extension or modification of the logging methods and their associated log levels:

The default logging methods and their log levels are as follows:

levels = {
    error: 1,
    warn: 2,
    info: 3,
    log: 4,
    debug: 4
};

The extend option enables the usage of custom console logging methods to be used with this module, for example:

// Extending the console with a custom method
console.fatal = function(msg) {
    console.org.error(msg);
    process.exit(1);
}

// Initialising the output formatter
require( 'console-stamp' )( console, {
    extend: {
        fatal: 1
    }
} );

Note how the console.org.error method used in the custom method. This is to prevent circular calls to console.error

API

require( 'console-stamp' )( console, [options] );

console

The global console or custom console.

options {Object|String}

The second parameter is an object with several options. As a feature this parameter can be a string containing the date-format.

• options.format {String}
  A string with date format based on dateformat
  Default: ':date(dd.mm.yyyy HH:MM:ss.l) :label'

• options.tokens {Object}
  Containing token-functions. See example here.

• options.include {Array}
  An array containing the methods to include in the patch
  Default: ["debug", "log", "info", "warn", "error"]

• options.level {String}
  A string choosing the most verbose logging function to allow.
  Default: log

• options.extend {Object}
  An object describing methods and their associated log level, to extend the existing method <-> log level pairs.
  For an example see Custom methods.

• options.stdout {WritableStream}
  A custom stdout to use with custom console.
  Default: process.stdout

• options.stderr {WritableStream}
  A custom stderr to use with custom console.
  Default: options.stdout or process.stderr

• options.preventDefaultMessage {Boolean}
  If set to true Console-stamp will not print out the standard output from the console. This can be used in combination with a custom message token.
  Default: false