https://github.com/fent/node-newsemitter

An event emitter that emits only new events.
https://github.com/fent/node-newsemitter

eventemitter node

Last synced: about 2 months ago
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An event emitter that emits only new events.

• Host: GitHub
• URL: https://github.com/fent/node-newsemitter
• Owner: fent
• License: mit
• Created: 2012-03-12T15:39:07.000Z (over 12 years ago)
• Default Branch: master
• Last Pushed: 2020-12-12T01:36:25.000Z (almost 4 years ago)
• Last Synced: 2024-07-22T05:33:27.828Z (about 2 months ago)
• Topics: eventemitter, node
• Language: TypeScript
• Homepage:
• Size: 102 KB
• Stars: 9
• Watchers: 3
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# node-newsemitter

An event emitter that emits only new events. Because sometimes we don't care about old events.

![Depfu](https://img.shields.io/depfu/fent/node-newsemitter)

[![codecov](https://codecov.io/gh/fent/node-newsemitter/branch/master/graph/badge.svg)](https://codecov.io/gh/fent/node-newsemitter)

# Usage

```js

const NewsEmitter = require('newsemitter');

const news = new NewsEmitter();

news.on('item', (item) => {

  console.log('new item:', item.title);

});

news.emit('item', { title: 'hello there' });

news.emit('item', { title: 'hello world' });

news.emit('item', { title: 'hello there' });

news.emit('item', { title: 'hey' });

news.emit('item', { title: 'hey' });

news.emit('item', { title: 'hey' });

// new item: hello there

// new item: hello world

// new item: hey

```

# API

### new NewsEmitter([options])

Creates an instance of a NewsEmitter. `options` can be

* `filter` - An array of events that will be affected. If not given, event names will not be filtered.

* `ignore` - An array of events that will be ignored. Defaults to `['newListener', 'removeListener']`.

* `maxHistory` - Maximum number of history items to remember. Default is `10`.

* `manageHistory` - If true, does not add emitted events to history. Instead expects you to manually manage history with `addHistory()`. Defaults to `false`.

* `identifier` - Function used to compare one event to another. Called with a list of arguments that `NewsEmitter#emit()` is called with, sans event name. Should return a string. Default is `JSON.stringify`.

### NewsEmitter#emit(event)

Emits an event, only if it has not been emitted before. Returns true if item is new and emtted. False otherwise.

### NewsEmitter#reset([event])

Resets history of an event. If no event given, resets all history.

### NewsEmitter#addHistory(event, arr)

Adds items in `arr` as `event`'s history. Truncated as necessary based on max history length considering the last item in the array as newest.

# Install

    npm install newsemitter

# Tests

Tests are written with [mocha](https://mochajs.org)

```bash

npm test

```