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About
Structured, multilevel & hierarchical loggers based on @thi.ng/rstream.
This package provides extensible, multi-level & multi-hierarchy logging infrastructure, with logged values transformable via @thi.ng/transducers. Several built-in transformers are provided.
The Logger class in this package implements the
@thi.ng/logger
ILogger interface and uses LogLevel enums to configure levels /
filtering. See that package for more details.
Status
STABLE - used in production
Search or submit any issues for this package
Support packages
- @thi.ng/rstream-log-file - File output handler for structured, multilevel & hierarchical loggers based on @thi.ng/rstream
Related packages
- @thi.ng/logger - Basis types for arbitrary & hierarchical logging
Installation
yarn add @thi.ng/rstream-log
ESM import:
import * as rslog from "@thi.ng/rstream-log";
Browser ESM import:
<script type="module" src="https://esm.run/@thi.ng/rstream-log"></script>
For Node.js REPL:
const rslog = await import("@thi.ng/rstream-log");
Package sizes (brotli'd, pre-treeshake): ESM: 749 bytes
Dependencies
Note: @thi.ng/api is in most cases a type-only import (not used at runtime)
API
```ts tangle:export/readme.ts import { LogLevel } from "@thi.ng/logger"; import { Logger, formatString, writeConsole } from "@thi.ng/rstream-log";
const logger = new Logger("main"); // or with min level const logger = new Logger("main", LogLevel.DEBUG); // or min level given as string const logger = new Logger("main", "DEBUG");
// add console output w/ string formatter (a transducer) // each logger instance has a rstream Stream instance // allowing for downstream processing logger.stream.transform(formatString()).subscribe(writeConsole());
logger.debug("hello world"); // [DEBUG] main: 2024-02-16T20:38:11.143Z hello world
logger.warn("eek"); // [WARN] main: 2024-02-16T20:38:11.144Z eek
// loggers can form hierarchies by creating/attaching child loggers const child = logger.childLogger("child", LogLevel.INFO);
import { postWorker } from "@thi.ng/rstream"; // additionally send messages from this logger to worker child.stream.subscribe(postWorker("log-worker.js"));
child.info("hi from submodule"); // [INFO] child: 2024-02-16T20:38:11.145Z hi from submodule
## Authors
- [Karsten Schmidt](https://thi.ng)
If this project contributes to an academic publication, please cite it as:
```bibtex
@misc{thing-rstream-log,
title = "@thi.ng/rstream-log",
author = "Karsten Schmidt",
note = "https://thi.ng/rstream-log",
year = 2017
}
License
© 2017 - 2025 Karsten Schmidt // Apache License 2.0