@hacker-und-koch/logger

Table Of Content

• Creating a Logger
• Log Levels
• Line Formatting
• LoggerBuilder

Creating a Logger

Builder pattern

const loggerBuilder: LoggerBuilder = Logger.build();

loggerBuilder.className('MyClass');  // manditory!

const logger: Logger = loggerBuilder.create();

logger.log('lorem ipsum');

Via Dependency Injection

import { Injectable } from '@hacker-und-koch/di';
import { Logger } from '@hacker-und-koch/logger';

@Injectable()
class MyClass {
    constructor(private logger: Logger) {
        this.logger.log('lorem ipsum');
    }
}

Log Levels

Order Of Significance

Highest to lowest:

• error
• warning
• log
• info
• spam

Calling logger by level

logger.spam('lorem');
logger.info('ipsum');
logger.log('dolor');
logger.warn('sit');
logger.error('amet');

Line Formatting

Default formatting (example)

Above examples will print

2020-01-02T03:04:50.001Z  -  MyClass: lorem
2020-01-02T03:04:50.002Z (i) MyClass: ipsum
2020-01-02T03:04:50.003Z     MyClass: dolor
2020-01-02T03:04:50.004Z [x] MyClass: sit
2020-01-02T03:04:50.005Z !!! MyClass: amet

Overwriting FormatFunction

const formatFunction: FormatFunction = (pkg: LoggerPackage): Buffer | string => {
    const argsAsString = pkg.parts
        .map(arg => arg.toString())
        .join('+++');
    return `[${pkg.class}] ${argsAsString}\n`;
}

const logger: Logger = Logger.build()
    .className('MyClass')
    .format(formatFunction)
    .create();

logger.log('lorem', 'ipsum');

prints

[MyClass] lorem+++ipsum

LoggerBuilder

className(className: string): this

Set class name to be used when formatting log output. (( manditory! ))

@param {string:} className Class name used when formatting log output.

create(): Logger

Calling this function will finish the building process. A new instance of Logger will be created and configured according to the LoggerBuilder's state.

id(id: string): this

Set ID of instance. Is utilized by di package.

@param id: ID of instance to be used when formatting log output.

level(level: Loglevel): this

Set threshold level for Logger. Only logs with level of equal or greater importance to this value will be printed.

@param level: Threshold level for Logger

format(format: FormatFunction): this

Set Logger's FormatFunction.

@param format: Mapping function to format log lines

stdout(stream: NodeJS.WriteStream): this

WriteStream used for levels 'spam', 'info' and 'log'.

@param stream: stdout stream

stderr(stream: NodeJS.WriteStream): this

WriteStream used for levels 'warning' and 'error'.

@param stream: stdout stream

noTimestamp(): this

If called: Logger's formating function will not include a timestamp