This project is part of the @thi.ng/umbrella monorepo.

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  • Log levels
  • Supplied implementations
  • Lazy evaluation
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Types & basis infrastructure for arbitrary logging (w/ default impls).

The types & implementations provided by this package are used in various places throughout the thi.ng/umbrella ecosystem and can be swapped out on demand to customize users' needs.

All loggers based on this basic framework provided by this package support the following LogLevels (in order of importance):

• FINE
• DEBUG
• INFO
• WARN
• SEVERE

Logging calls targetting lower levels than configured in the logger will be ignored.

The following logger implementations are provided:

• ConsoleLogger: writes output to console
• MemoryLogger: writes output to in-memory journal
• NULL_LOGGER: no-op logger, suppresses all output

Log messages can contain any number & types of arguments. No-arg functions can be provided as message arg to avoid evaluation of potentially costly message formatting for suppressed log levels. For example:

import { ConsoleLogger, LogLevel } from "@thi.ng/logger";

const logger = new ConsoleLogger("app", LogLevel.INFO);

const name = "thi.ng";

// eager (standard) arg evaluation
logger.info(`hello, ${name}`);
// [INFO] app: hello, thi.ng

// eager (standard) arg evaluation, but suppressed output
logger.debug("result is", 23 + 42);

// lazy arg evaluation
logger.info("result is", () => 23 + 42);
// [INFO] app: result is 65

STABLE - used in production

Search or submit any issues for this package

• @thi.ng/rstream-log - Structured, multilevel & hierarchical loggers based on @thi.ng/rstream

yarn add @thi.ng/logger

ES module import:

<script type="module" src="https://cdn.skypack.dev/@thi.ng/logger"></script>

Skypack documentation

For Node.js REPL:

# with flag only for < v16
node --experimental-repl-await

> const logger = await import("@thi.ng/logger");

Package sizes (gzipped, pre-treeshake): ESM: 553 bytes

None

Several demos in this repo's /examples directory are using this package.

A selection:

Screenshot	Description	Live demo	Source
	Drawing to floating point offscreen / multi-pass shader pipeline	Demo	Source

Generated API docs

TODO

Karsten Schmidt

If this project contributes to an academic publication, please cite it as:

@misc{thing-logger,
  title = "@thi.ng/logger",
  author = "Karsten Schmidt",
  note = "https://thi.ng/logger",
  year = 2016
}

© 2016 - 2022 Karsten Schmidt // Apache Software License 2.0