Class Logger

main Logger class. provides hierarchical logging with customizable transports, formatters, and scopes. supports child loggers for organized logging across application components.

Example: basic usage

const logger = new Logger('myapp');
logger.info('hello world');

Example: with child loggers

const dbLogger = logger.child('database');
dbLogger.error('connection failed');

Example: with custom transports

const logger = new Logger('app');
logger.addTransport(new FileTransport({ filename: 'app.log' }));
logger.info('logged to both console and file');

Index

Constructors

constructor

Methods

addTransport child clearTransports debug error fatal info removeTransport trace warn withMetadata getGlobalLevel setGlobalLevel

Constructors

constructor

new Logger(scope?: string | string[], options?: LoggerOptions): Logger
creates a new Logger instance.
Parameters
- scope: string | string[] = []
  the scope name(s) for this logger. can be a string or array of strings
- options: LoggerOptions = {}
  configuration options including level, timestamp, colourization, and metadata
Returns Logger
Example: single scope
```
const logger = new Logger('api');
```
Example: multiple scopes
```
const logger = new Logger(['app', 'database', 'users']);
```
Example: with options
```
const logger = new Logger('debug-logger', {
  level: LogLevel.DEBUG,
  colourize: false,
  metadata: { version: '1.0.0' }
});
```
- Defined in logger.ts:72

Methods

addTransport

addTransport(transport: Transport): void
adds a transport to this logger instance. transports determine where log entries are sent (console, file, network, etc.).
Parameters
- transport: Transport
  the transport to add
Returns void
Example
```
logger.addTransport(new FileTransport({ filename: 'app.log' }));
logger.addTransport(new HttpTransport({ url: 'https://api.example.com/logs' }));
```
- Defined in logger.ts:123

child

child(scope: string | string[], options?: LoggerOptions): Logger
creates a child logger with additional scope. child loggers inherit all transports from their parent.
Parameters
- scope: string | string[]
  additional scope to append to the current scope
- options: LoggerOptions = {}
  options to override from parent logger
Returns Logger
new Logger instance with extended scope
Example: single scope
```
const apiLogger = logger.child('api');
apiLogger.info('api request received'); // logs with scope ['app', 'api']
```
Example: multiple scopes
```
const authLogger = apiLogger.child(['auth', 'login']);
// results in scope: ['app', 'api', 'auth', 'login']
```
Example: with options override
```
const debugLogger = logger.child('debug', { level: LogLevel.DEBUG });
```
- Defined in logger.ts:331

clearTransports

clearTransports(): void
removes all transports from this logger instance. after calling this, log entries will not be output anywhere until new transports are added.

Returns void
- Defined in logger.ts:143

debug

debug(message: string, ...args: unknown[]): void
logs a debug message. used for debugging information during development.
Parameters
- message: string
  the message to log
- ...args: unknown[]
  additional arguments to include
Returns void
Example
```
logger.debug('user data received', userData);
```
- Defined in logger.ts:242

error

error(message: string, ...args: unknown[]): void
logs an error message. used for error conditions that don't require immediate attention.
Parameters
- message: string
  the message to log
- ...args: unknown[]
  additional arguments to include
Returns void
Example
```
logger.error('failed to process request', error);
```
- Defined in logger.ts:287

fatal

fatal(message: string, ...args: unknown[]): void
logs a fatal message. used for severe error events that may lead to application termination.
Parameters
- message: string
  the message to log
- ...args: unknown[]
  additional arguments to include
Returns void
Example
```
logger.fatal('database connection lost', { attempts: 3 });
```
- Defined in logger.ts:302

info

info(message: string, ...args: unknown[]): void
logs an info message. used for general informational messages.
Parameters
- message: string
  the message to log
- ...args: unknown[]
  additional arguments to include
Returns void
Example
```
logger.info('server started on port 3000');
```
- Defined in logger.ts:257

removeTransport

removeTransport(transport: Transport): void
removes a specific transport from this logger instance.
Parameters
- transport: Transport
  the transport instance to remove
Returns void
- Defined in logger.ts:132

trace

trace(message: string, ...args: unknown[]): void
logs a trace message. used for very detailed debugging information.
Parameters
- message: string
  the message to log
- ...args: unknown[]
  additional arguments to include
Returns void
Example
```
logger.trace('entering function', { functionName: 'processUser' });
```
- Defined in logger.ts:227

warn

warn(message: string, ...args: unknown[]): void
logs a warning message. used for potentially harmful situations.
Parameters
- message: string
  the message to log
- ...args: unknown[]
  additional arguments to include
Returns void
Example
```
logger.warn('deprecated api endpoint used', { endpoint: '/old-api' });
```
- Defined in logger.ts:272

withMetadata

withMetadata(metadata: Record<string, unknown>): Logger
creates a new logger instance with additional metadata. useful for adding context information to all log entries from this logger.
Parameters
- metadata: Record<string, unknown>
  additional metadata to merge with existing metadata
Returns Logger
new logger instance with combined metadata
Example
```
const requestLogger = logger.withMetadata({
  requestId: 'req-123',
  userId: 'user-456'
});

requestLogger.info('processing request');
// all logs will include the requestId and userId metadata
```
- Defined in logger.ts:368

`Static`getGlobalLevel

getGlobalLevel(): LogLevel
gets the current global log level.

Returns LogLevel
the current global log level
- Defined in logger.ts:107

`Static`setGlobalLevel

setGlobalLevel(level: LogLevel): void
sets the global log level for all logger instances. affects all existing and future logger instances unless they have an explicit level set.
Parameters
- level: LogLevel
  the log level to set globally
Returns void
Example
```
Logger.setGlobalLevel(LogLevel.DEBUG);
// all loggers will now log debug messages and above
```
- Defined in logger.ts:98

Class Logger

Example: basic usage

Example: with child loggers

Example: with custom transports

Index

Constructors

Methods

Constructors

constructor

Parameters

Returns Logger

Example: single scope

Example: multiple scopes

Example: with options

Methods

addTransport

Parameters

Returns void

Example

child

Parameters

Returns Logger

Example: single scope

Example: multiple scopes

Example: with options override

clearTransports

Returns void

debug

Parameters

Returns void

Example

error

Parameters

Returns void

Example

fatal

Parameters

Returns void

Example

info

Parameters

Returns void

Example

removeTransport

Parameters

Returns void

trace

Parameters

Returns void

Example

warn

Parameters

Returns void

Example

withMetadata

Parameters

Returns Logger

Example

StaticgetGlobalLevel

Returns LogLevel

StaticsetGlobalLevel

Parameters

Returns void

Example

Settings

On This Page

`Static`getGlobalLevel

`Static`setGlobalLevel