simple winston inspired wrapper for cross lib logging
npm install @decaf-ts/loggingDecaf’s logging toolkit keeps one fast MiniLogger at the core while exposing adapters, filters, and utilities that fit both browser and Node.js runtimes:
- Configure once through Logging.setConfig or the Environment accumulator and let impersonated child loggers inherit overrides without allocations.
- Apply filter chains, transports, and adapter-specific features (Pino, Winston, custom factories) through the shared LoggingConfig contract.
- Instrument classes using decorators, LoggedClass, and Logging.because while StopWatch, text/time utilities, and environment helpers round out the diagnostics surface.
* Logging: A static class for managing global logging configuration and creating logger instances.
* MiniLogger: A lightweight, default logger implementation.
* LoggedClass: An abstract base class that provides a pre-configured logger instance to its subclasses.
* LoggedEnvironment: A class for managing environment-specific logging configurations.
* Decorators: A set of decorators (@log, @benchmark, etc.) for easily adding logging and benchmarking to your methods.
* Filters and Transports: A system for filtering sensitive information and transporting logs to different destinations.
* Pino and Winston Integration: Built-in support for two popular logging libraries, Pino and Winston.
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Documentation available here
Minimal size: 6.2 KB kb gzipped
The logging package is a lightweight, extensible logging solution for TypeScript projects. It centers on two main constructs:
- MiniLogger — a minimal, context-aware logger used by default.
- Logging — a static facade that manages global configuration, creates loggers for classes/functions/strings, and applies optional theming.
It also offers:
- A concise set of decorators (log, debug, info, verbose, silly) to instrument methods with consistent logging and optional benchmarking.
- Pluggable factories so that alternate implementations (e.g., WinstonLogger) can be used without changing call sites.
- Strong typing for configuration and theming primitives.
Core files and their roles
- src/types.ts: Type definitions and contracts
- Logger: the runtime contract with methods silly, verbose, info, debug, error, for, setConfig.
- LoggingConfig: runtime configuration for filtering, formatting, and styling.
- LoggerFactory: factory signature returning a Logger for a given context and optional config.
- Theme/ThemeOption/ThemeOptionByLogLevel: shape of color and style configuration, optionally varying by LogLevel.
- Additional helpers: StringLike, AnyFunction, Class, LoggingContext.
- src/constants.ts: Defaults and enums
- LogLevel: error | info | verbose | debug | silly (string values), plus NumericLogLevels for filtering.
- LoggingMode: RAW | JSON (current implementation focuses on RAW; JSON is available for adapters like Winston).
- DefaultTheme: sensible default colors/styles per component and per log level.
- DefaultLoggingConfig: default global configuration (info level, no styling, timestamp on, etc.).
- src/logging.ts: Implementations and static facade
- MiniLogger: A small, dependency-light logger that:
- Generates formatted log strings (timestamp, log level, context, correlation id, message, stack) according to config.
- Supports child loggers via .for(method|config) with a Proxy to overlay per-child config and extend the context (class.method).
- Emits to console.log/console.debug/console.error based on level. Verbosity controls .silly output (gated by config.verbose).
- Logging: The static entry point that:
- Holds global configuration (Logging.getConfig(), Logging.setConfig()).
- Creates loggers for arbitrary contexts (Logging.for(object|class|function|string, config?)).
- Provides convenience static logging methods (info, debug, error, verbose, silly) delegating to a global logger instance.
- Supports theming (Logging.theme) by applying Theme options through styled-string-builder when style=true.
- Allows replacing the logger factory (Logging.setFactory) to integrate with other backends (e.g., Winston).
- src/decorators.ts: Method decorators
- log(level=info, benchmark=false, verbosity=0): wraps a method to emit a call log and optionally a completion time; supports Promise-returning methods.
- debug/info/silly/verbose: concise wrappers around log() for common patterns.
- src/LoggedClass.ts: Base convenience class
- LoggedClass exposes a protected this.log getter returning a context-aware Logger built via Logging.for(this), simplifying logging inside class methods.
- src/winston/winston.ts: Optional Winston adapter
- WinstonLogger: extends MiniLogger but delegates emission to a configured Winston instance.
- WinstonFactory: a LoggerFactory you can install with Logging.setFactory(WinstonFactory) to globally route logs through Winston.
Design principles
- Minimal by default: Console output with small surface area and no heavy dependencies (except styled-string-builder when style is enabled).
- Config-driven: Behavior (level thresholds, verbosity, timestamps, separators, theming) is controlled via LoggingConfig.
- Context-first: Log context is explicit ("MyClass" or "MyClass.method"), aiding filtering and debugging.
- Extensible: Swap logger implementations via a factory; MiniLogger serves as a reference implementation.
- Safe theming: Logging.theme guards against invalid theme keys and values and logs errors instead of throwing.
Key behaviors
- Level filtering: NumericLogLevels are used to compare configured level with the message level and decide emission.
- Verbosity: .silly obeys LoggingConfig.verbose; only messages with <= configured verbosity are emitted.
- Theming and styling: When style=true, Logging.theme applies Theme rules per component (class, message, logLevel, id, stack, timestamp). Theme can vary per LogLevel via ThemeOptionByLogLevel.
- Correlation IDs: If correlationId is configured in a logger or child logger, it is included in output for easier traceability.
Public API surface
- Classes: MiniLogger, Logging, LoggedClass; WinstonLogger (optional).
- Decorators: log, debug, info, verbose, silly.
- Enums/Consts: LogLevel, LoggingMode, NumericLogLevels, DefaultTheme, DefaultLoggingConfig.
- Types: Logger, LoggingConfig, LoggerFactory, Theme, ThemeOption, ThemeOptionByLogLevel, LoggingContext.
Intended usage
- Use Logging.setConfig() at application startup to set level/style/timestamps.
- Create class- or method-scoped loggers via Logging.for(MyClass) or logger.for('method').
- Adopt LoggedClass to remove boilerplate in classes.
- Add decorators to methods for automatic call/benchmark logs.
- For advanced deployments, swap to WinstonFactory.
This guide provides examples of how to use the main features of the @decaf-ts/logging library.
You can set the initial logging configuration using Logging.setConfig().
``typescript
import { Logging, LogLevel } from '@decaf-ts/logging';
Logging.setConfig({
level: LogLevel.debug,
style: true,
timestamp: true,
});
`
The logging framework uses a proxy-based impersonation mechanism to create child loggers. This provides a significant performance gain by avoiding the need to create new logger instances for each context.
`typescript
import { Logging } from '@decaf-ts/logging';
const rootLogger = Logging.get();
const childLogger = rootLogger.for('MyClass');
// childLogger is a proxy that inherits the configuration of rootLogger
childLogger.info('This is a message from the child logger');
`
Filters allow you to process log messages before they are written. You can use them to filter out sensitive information.
`typescript
import { Logging, PatternFilter } from '@decaf-ts/logging';
// Filter out passwords
const passwordFilter = new PatternFilter(/password/i, '**');
Logging.setConfig({
filters: [passwordFilter],
});
const logger = Logging.get();
logger.info('User logged in with password: mysecretpassword');
// Output will be: User logged in with password: **
`
Transports are responsible for writing log messages to a destination. The library includes a default console transport, and you can create your own.
Note: The library currently focuses on filters and logger implementation, with transport-like functionality being a feature of the underlying adapters (Pino, Winston).
The library includes built-in support for Pino and Winston.
`typescript
import { Logging } from '@decaf-ts/logging';
import { pino } from 'pino';
import { PinoLogFactory } from '@decaf-ts/logging/pino';
const pinoInstance = pino();
Logging.setFactory(new PinoLogFactory(pinoInstance));
const logger = Logging.get();
logger.info('This message will be logged by Pino');
`
`typescript
import { Logging } from '@decaf-ts/logging';
import * as winston from 'winston';
import { WinstonLogFactory } from '@decaf-ts/logging/winston';
const winstonInstance = winston.createLogger({
transports: [new winston.transports.Console()],
});
Logging.setFactory(new WinstonLogFactory(winstonInstance));
const logger = Logging.get();
logger.info('This message will be logged by Winston');
`
The LoggedEnvironment class allows you to manage environment-specific logging configurations.
`typescript
import { LoggedEnvironment } from '@decaf-ts/logging';
// Set the application name
LoggedEnvironment.app = 'MyAwesomeApp';
// Accumulate additional environment configuration
LoggedEnvironment.accumulate({
database: {
host: 'localhost',
port: 5432,
},
});
`
The LoggedClass is an abstract base class that provides a pre-configured logger instance to its subclasses.
`typescript
import { LoggedClass } from '@decaf-ts/logging';
class MyService extends LoggedClass {
doSomething() {
this.log.info('Doing something...');
}
}
const service = new MyService();
service.doSomething();
`
The library provides a set of decorators for easily adding logging and benchmarking to your methods.
`typescript
import { log, LogLevel } from '@decaf-ts/logging';
class MyDecoratedService {
@log(LogLevel.info)
myMethod(arg1: string) {
// ...
}
}
`
`typescript
import { benchmark } from '@decaf-ts/logging';
class MyBenchmarkedService {
@benchmark()
myLongRunningMethod() {
// ...
}
}
``
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This project is released under the MIT License.
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