Notoriously Punctual Manatee

    TypeScript icon, indicating that this package has built-in type declarations

    0.0.9 • Public • Published

    To install

    npm install --save logbok

    To create a logger for a class

    export class MyClass {
        private static readonly logger = Logbok.getLogger(MyClass);

    Or for a vanilla javascript function

    var logger;
    function myFunction() {
        logger = logger || Logbok.getLogger(myFunction);

    To log specific messages

    logger.debug('this is a debug log');'this is an info log');
    logger.warn('this is a warn log');
    logger.error('this is an error log');


    Logbok reads the specified configuration from its CONFIG property.
    Currently supported configurable parameters are log-level, disabled-loggers, and log-appenders.

    log-level string can be either debug, info, warn, and error - with debug as the lowest and error as the highest level, respectively - initially set to debug. Logbok.CONFIG['log-level'] = 'debug'
    disabled-loggers array contains the list of the classes/types whose loggers will be disabled - initially set to empty. Logbok.CONFIG['disabled-loggers'] = [MyClass]
    log-appenders array contains the list of instances of log appenders to be used - initially set to empty.
    Currently, Logbok provides 5 appenders, namely, ConsoleLogAppender, ChromeConsoleLogAppender, NodeConsoleLogAppender, IsoTimestampAppender, and RollingFileAppender
    Logbok.CONFIG['log-appenders'] = [ new ChromeConsoleLogAppender(), new CustomLogAppender() ]

    ***Note: All of the above mentioned attributes are configured in a way that when a new value is assigned, the changes will be applied immediately.

    Creating a custom log appender

    If the provided appenders are insufficient, you can extend those and/or make your own log appender for your own specific usecase.
    You just need to implement the Appender interface like below:

    // this is a blunt angular sample for a remote log appender implementation
    export class RemoteLogAppender implements Appender {
        readonly appenderName = 'RemoteLogAppender';
        private static readonly chromeConsoleLogAppender = new ChromeConsoleLogAppender();
        log(logEntry: LogEntry): void {
            const message = logEntry.buildLogString('');
  'https://log/service/url', message, /*httpOptions*/).subscribe(() => {
    // then somewhere up the initialization phase
    Logbok.CONFIG['log-appenders'] = [ new RemoteLogAppender() ]

    For reference purposes, the appender interface is defined in Logbok as

    export interface Appender {
        readonly appenderName: string;
        log(logEntry: LogEntry): void;

    Sample Codes

    Vanilla javascript code snippet for Node JS:

    var { Logbok, ConsoleLogAppender } = require("logbok");
    var logger;
    function myFunction() {
       logger = logger || Logbok.getLogger(myFunction);'this is an info log');
    Logbok.CONFIG['log-appenders'] = [new ConsoleLogAppender()]
    myFunction(); // prints something like "04/24/2019 - 15:30:29.958 INFO [myFunction] - this is an info log"

    Code snippet for Typescript:

    import { Logbok, ConsoleLogAppender } from "logbok";
    export class MyClass {
        private static readonly logger = Logbok.getLogger(MyClass);
        log() {
  'this is an info log');
    Logbok.CONFIG['log-appenders'] = [ new ConsoleLogAppender() ];
    new MyClass().log(); // prints something like "04/24/2019 - 15:46:33.891 INFO [MyClass] - this is an info log"

    Log Appenders

    Logbok comes with 5 core log appenders, namely, ConsoleLogAppender, ChromeConsoleLogAppender, NodeConsoleLogAppender, IsoTimestampAppender, and RollingFileAppender. Each one has a different usecase but some can be used in conjunction with one another (e.g. RollingFileAppender can be paired with either of the three: ConsoleLogAppender, NodeConsoleLogAppender, IsoTimestampAppender).

    • #### ConsoleLogAppender This is the most basic log appender among all logbok appenders.
      This one is built on top of the console object, hence the name.
      No magic and all, just plain text pre-formatted to look like a decent log message.
      Below is a sample snippet of the output of a ConsoleLogAppender.


    • #### IsoTimestampAppender This one is time-formatted version of ConsoleLogAppender.
      No magic and all, just plain text with pre-formatted time to look like a decent log message.
      Below is a sample snippet of the output of a IsoTimestampAppender.


    • #### ChromeConsoleLogAppender This one is a color-coded version of ConsoleLogAppender dedicated for Chrome/Chrome-based renderer apps (e.g. Electron)
      Below is a sample snippet of the output of a ChromeConsoleLogAppender.


    • #### NodeConsoleLogAppender This one is similar to ChromeConsoleLogAppender in the manner that it is also a color-coded version of ConsoleLogAppender.
      The only difference is that this one is for the command line/terminal window console instead of the chrome.
      Below is a sample snippet of the output of a NodeConsoleLogAppender.


    • #### RollingFileAppender This one is more advanced compared to the other types of appender. The idea is that it redirects logs to a file instead of using a console object.
      Currently, this can only be used by backend codes, as it requires collocation of the log file with the running instance.
      This appender can be instantiated with the following optional parameters:

      filePath string the path of the file where to write the logs, creates it if it does not exist yet default value is './logbok.log'
      rolloverOption RolloverOption the rollover mechanism describing when to rename the current log file with a new rollover filename. see below description of possible values naming follows counting numbers starting from 1, e.g. for filepath='./server.log' rollover files will be server-1.log, server-2.log, and so on.
       export declare interface RolloverOption {
           size?: RolloverSize,
           sizeInKiB?: number
           sizeInMiB?: number,
           sizeInGiB?: number,
           timeInterval?: RolloverTime,
           timeIntervalInSeconds?: number,
           timeIntervalInMinutes?: number,
           timeIntervalInHours?: number
       export enum RolloverTime {
       export enum RolloverSize {
           TEN_MiB, // is equal to (10 * 1024 * 1024) bytes
           FIFTY_MiB, // is equal to (5 * TEN_MiB) bytes
           HUNDRED_MiB, // is equal to (10 * TEN_MiB) bytes
           ONE_GiB, // is equal to (10 * 1024 * 1024 * 1024) bytes
           TEN_GiB // is equal to (10 * TEN_GiB) bytes

      Below are sample rollover configurations

       new RollingFileAppender('./server.log', { size: RolloverSize.TEN_MiB })       // rolls over everytime log file reaches 10MiB
       new RollingFileAppender('./server.log', { sizeInKiB: 100 }                    // rolls over everytime log file reaches 100KiB
       new RollingFileAppender('./server.log', { timeInterval: RolloverTime.HOURLY } // rolls over every 1 hour
       new RollingFileAppender('./server.log', { timeIntervalInSeconds: 10 }         // rolls over every 10 seconds


    npm i logbok

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