https://github.com/xpepermint/logmitter

Universal logging utility as event emitter.
https://github.com/xpepermint/logmitter

emit emitter event log logger logging

Last synced: 30 days ago
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Universal logging utility as event emitter.

Host: GitHub
URL: https://github.com/xpepermint/logmitter
Owner: xpepermint
License: mit
Created: 2019-09-29T09:28:43.000Z (over 5 years ago)
Default Branch: master
Last Pushed: 2021-08-11T12:46:43.000Z (over 3 years ago)
Last Synced: 2025-03-22T15:47:42.024Z (about 1 month ago)
Topics: emit, emitter, event, log, logger, logging
Language: TypeScript
Size: 221 KB
Stars: 2
Watchers: 2
Forks: 0
Open Issues: 7
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md

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Logmitter is a universal logging utility which acts as event emitter. It's a lightweight open-source package for the **server** and **browser** (using module bundler), written with [TypeScript](https://www.typescriptlang.org). It's actively maintained, well tested and already used in production environments. The source code is available on [GitHub](https://github.com/xpepermint/logmitter) where you can also find our [issue tracker](https://github.com/xpepermint/logmitter/issues).

## Installation

Run the command below to install the package.

```

$ npm install --save logmitter

```

## Usage

`Logger` class is an event emitter which provides standard methods for triggering and listening to different logging events. This class should be used as a central logger instance of your application.

### Listening and triggering events

We create a simple logger by creating a new instance of a `Logger` class. We can then emit and listen to different logging events. 

```ts

import { Logger, LogEvent } from 'logmitter';

const logger = new Logger(namespace);

logger.on(LogEvent.INFO, function({ date, event, message, namespace }) {

  console.info(message);

});

logger.info('Hello world!');

```

### Custom message format

We can easily change the message format by setting a custom message interface.

```ts

interface Message {

  code: number;

  message: any;

};

const logger = new Logger(namespace);

logger.warn({ code: 200, message: 'Hello world!' });

```

### Namespaced logger

To distinguish between application parts, you can namespace the logger instance by creating a child instance which passes all events to the master instance.

```ts

const userLogger = logger.child('user');

```

## API

**Logger(namespace)**

> Main logger class.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| namespace | String | No | - | Logger namespace.

**Logger.prototype.child(namespace)**: LoggerChild

> Returns logger child instance.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| namespace | String | No | - | Logger namespace.

**Logger.prototype.debug(message)**: Boolean

> Triggers `debug` event.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| message | Message | Yes | - | Event message.

**Logger.prototype.emit(event, message, namespace)**: Boolean

> Triggers log event.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| event | String | Yes | - | Event name.

| message | Message | Yes | - | Event message.

| namespace | String | No | this | Logger namespace.

**Logger.prototype.error(message)**: Boolean

> Triggers `error` event.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| message | Message | Yes | - | Event message.

**Logger.prototype.info(message)**: Boolean

> Triggers `info` event.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| message | Message | Yes | - | Event message.

**Logger.prototype.namespace**: string

> Returns logger namespace.

**Logger.prototype.off(event, resolver)**: Logger

> Removes attached event listener.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| event | String | Yes | - | Event name.

| resolver | Function, Promise | No | - | Event resolver function. All event with the provided name are removed when the resolver is not provided.

**Logger.prototype.on(event, resolver)**: Logger

> Attaches a listener function to log event.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| event | String | Yes | - | Event name.

| resolver | Function, Promise | Yes | - | Event resolver function.

**Logger.prototype.once(event, resolver)**: Logger

> Attaches a listener function to log the event and automatically removes it after the event is triggered.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| event | String | Yes | - | Event name.

| resolver | Function, Promise | Yes | - | Event resolver function.

**Logger.prototype.warn(message)**: Boolean

> Triggers `warn` event.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| message | Message | Yes | - | Event message.

**LoggerChild(parent, namespace)**

> Logger child class.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| parent | Logger | Yes | - | Parent logger class instance.

| namespace | String | Yes | - | Logger namespace.

**LoggerChild.prototype.child(namespace)**: LoggerChild

> Returns logger child instance.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| namespace | String | No | - | Logger namespace.

**LoggerChild.prototype.debug(message)**: Boolean

> Triggers `debug` event.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| message | Message | Yes | - | Event message.

**LoggerChild.prototype.error(message)**: Boolean

> Triggers `error` event.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| message | Message | Yes | - | Event message.

**LoggerChild.prototype.info(message)**: Boolean

> Triggers `info` event.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| message | Message | Yes | - | Event message.

**LoggerChild.prototype.namespace**: string

> Returns logger namespace.

**LoggerChild.prototype.warn(message)**: Boolean

> Triggers `warn` event.

| Option | Type | Required | Default | Description

|--------|------|----------|---------|------------

| message | Message | Yes | - | Event message.

### Available events

| Event | Value | Description

|--------|------|----------

| LogEvent.ERROR | error | Error event.

| LogEvent.WARN | warn | Warning event.

| LogEvent.INFO | info | Info event.

| LogEvent.DEBUG | debug | Debug event.

## Contributing

See [CONTRIBUTING.md](https://github.com/rawmodel/framework/blob/master/CONTRIBUTING.md) for how to help out.

## Licence

See [LICENSE](https://github.com/rawmodel/framework/blob/master/LICENCE) for details.

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