https://github.com/stagas/eventstack

Middleware for EventEmitters
https://github.com/stagas/eventstack

Last synced: 13 days ago
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Middleware for EventEmitters

• Host: GitHub
• URL: https://github.com/stagas/eventstack
• Owner: stagas
• License: mit
• Created: 2011-10-24T08:07:57.000Z (about 13 years ago)
• Default Branch: master
• Last Pushed: 2012-02-06T12:01:04.000Z (almost 13 years ago)
• Last Synced: 2024-10-10T18:14:21.948Z (about 1 month ago)
• Language: JavaScript
• Homepage:
• Size: 101 KB
• Stars: 6
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# EventStack

Middleware for EventEmitters

## Installation

`npm install eventstack`

## Description

Sometimes I wished I could take an event and apply some logic to it before

it reaches the listener. So I made this thingy.

It is still a regular EventEmitter, with an extra `.use()` method where you

use to add middleware to your events.

The API looks like this:

```javascript

ee.use('some event', function (args, next) {

  // do stuff here

  // ...

  

  // move on

  next();

});

```

The function is called in the EventEmitter context with 2 arguments,

`args` and `next`.

`args` is an `Array` with the event arguments, including the event name, you

can use to inspect or transform.

You call `next()` to move to the next middleware, or emit the event when

it reaches the end of the stack. It is not necessary to call `next()` all the

time, depending on your logic, you could use `this.emit(...)` to emit

a different event or even do nothing.

## Usage

Standalone:

```javascript

var ee = new EventStack();

```

Inherit (just like a regular EventEmitter):

```javascript

function Cat () {

  EventStack.call(this);

}

util.inherits(Cat, EventStack);

Cat.prototype.meow = function () {

  this.emit('meow');

}

```

Patch existing EventEmitter:

```javascript

var ee = new EventEmitter();

EventStack(ee); // patched!

ee.use(...);

```

## Example

```javascript

var EventStack = require('eventstack');

var ee = new EventStack;

// add a middleware that waits for `bar` messages on `foo`

// and re-emits `foobar!` to `bar`!

ee.use('foo', function (args, next) {

  if (args[1] === 'bar') {

    this.emit('bar', 'foobar!');

  } else {

    next();

  }

});

ee.on('foo', function (s) {

  console.log('listener foo:', s);

});

ee.on('bar', function (s) {

  console.log('listener bar:', s);

});

ee.emit('foo', 'not bar :(');

ee.emit('foo', 'bar');

```

## Licence

MIT/X11