@torgeilo/logger

Tiny, customizable logger, designed for the browser.

Features

• Namespaces.
• Pluggable log handlers.
• Typed and customizable log levels (called tags internally).
• Basic minimal console log handler (default).
• Styled console log handler (separate bundle).
• No dependencies.

Getting started

Install:

npm install @torgeilo/logger

Use:

import { getLogger } from '@torgeilo/logger';

const logger = getLogger('my namespace');

logger.log('Hello');
logger.debug('world');

Default console output of the above, with log levels "log" and "debug":

my namespace: Hello
my namespace: world

Default log levels: debug, log, info, warn, error.

Customizing

Disable logging

Empty the logHandlers array however you prefer. A clear() method is added for convenience:

import { logHandlers } from '@torgeilo/logger';

logHandlers.clear();

Styled console log handler

Import and add the styled console log handler to the logHandlers array.

import { logHandlers } from '@torgeilo/logger';
import { StyledConsoleLogHandler } from '@torgeilo/logger/styled-console-log-handler.js';

logHandlers.clear(); // Remove the default log handler.
logHandlers.push(new StyledConsoleLogHandler());

Custom log levels/tags

import { getLogger } from '@torgeilo/logger';

const logger = getLogger<'Finn' | 'Jake'>('Together Again');

logger.Finn('Oh, man, are they angry!');
logger.Jake('Angry and fresh outta ice cream!');

Default console output (with level log):

Together Again/Finn: Oh, man, are they angry!
Together Again/Jake: Angry and fresh outta ice cream!

Custom log handler

Implement the LogHandler interface and add your implementation to the logHandlers array. The interface:

export interface LogHandler {
  log(namespace: string, tag: string, message: unknown, ...messages: unknown[]): void;
}

The tag is typically the log level, which can be checked using isLogLevel():

import { isLogLevel } from '@torgeilo/logger';

const tag = ...;
const message = ...;

if (isLogLevel(tag)) {
  console[tag](message);
} else {
  console.log(`${tag}:`, message);
}

Possibilities

You could:

• Make a log handler which only outputs errors or warnings.
• Make a log handler which shows the log in an HTML element on screen.
• Make a log handler which sends errors to a remote error tracker.
• Make a log handler which sends a custom tag to a remote tracker, like logger.metric(123);.
• Make a test reporter which logs the test run output, and a log handler which sends it somewhere useful, in addition to the console.

License

This software is licensed under the terms of the MIT license.

Contributing

Smaller bug reports are welcome.

I don't have capacity for much else. You're probably better off forking if you want to change things.