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Logger

Abstract class that represents a logging system. Extend this class with a real implementation depending on the environment (node/browser).

constructor​

Class constructor.

public constructor();

Usage​

const logger = new Logger();

debug​

Information that is diagnostically helpful to people more than just developers (IT, sysadmins, etc.). This should be the minimum logging level in development.

public abstract debug(...args: unknown[]): void;

Parameters​

  • ...args: Parameters to log.

Usage​

logger.debug('Message...');

info​

Generally useful information to log (service start/stop, configuration assumptions, etc). Info we want to always have available but usually don't care about under normal circumstances. This should be the minimum logging level in (pre)production.

public abstract info(...args: unknown[]): void;

Parameters​

  • ...args: Parameters to log.

Usage​

logger.info('Message...');

warn​

Anything that can potentially cause application oddities, but which is not a serious concern (such as switching from a primary to backup server, retrying an operation, missing secondary data, etc.). Not much to worry about, but it is still important to analyze warnings on a regular basis to identify potential issues.

public abstract warn(...args: unknown[]): void;

Parameters​

  • ...args: Parameters to log.

Usage​

logger.warn('Message...');

error​

Any error which is fatal to the operation, but not the service or application (can't open a required file, missing data, etc.). These errors will force user (administrator, or direct user) intervention. These are usually reserved for incorrect connection strings, missing services, uncaught exceptions, etc. Constitutes a degradation of service, which means engineering team must be immediately notified.

public abstract error(...args: unknown[]): void;

Parameters​

  • ...args: Parameters to log.

Usage​

logger.error('Message...');

fatal​

Any error that is forcing a shutdown of the service or application to prevent data loss (or further data loss). Reserved only for the most heinous errors and situations where there is guaranteed to have been data corruption or loss. Constitutes an interruption of service, which means engineering and SysAdmin / DevOps teams must be immediatly notified.

public abstract fatal(...args: unknown[]): void;

Parameters​

  • ...args: Parameters to log.

Usage​

logger.fatal('Message...');

close​

Gracefully closes the logging system (before stopping the program, for instance).

public abstract close(): Promise<void>;

Usage​

await logger.close();