https://github.com/gfarrell/event.js

Simple event pub/sub for Javascript, trying to plug the gaps left by other Event libraries like Microevent
https://github.com/gfarrell/event.js

Last synced: about 22 hours ago
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Simple event pub/sub for Javascript, trying to plug the gaps left by other Event libraries like Microevent

• Host: GitHub
• URL: https://github.com/gfarrell/event.js
• Owner: gfarrell
• Created: 2014-06-12T15:43:25.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2014-08-05T12:07:04.000Z (over 10 years ago)
• Last Synced: 2025-01-16T16:17:10.574Z (1 day ago)
• Language: JavaScript
• Size: 203 KB
• Stars: 0
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Event.js - Small event pub/sub library

Event.js tries to plug the gaps in other event pub/sub bind/trigger or whatever-method-you-use libraries. It's extremely simple, but shouldn't do anything you don't expect.

## Usage

Let's start by `require()`ing Event.js and creating an instance:

    Vent    = require('EventJS');

    MyEvent = new Vent();

### Subscribing to an event

To subscribe a callback to an event, simply use `subscribe(name, callback)`:

    MyEvent.subscribe('test', myCallback);

If you are using the method of a particular object, then use the `bind` argument:

    MyEvent.subscribe('test', myFoo.myCallback, myFoo);

This will ensure that `myFoo.myCallback` is bound to `myFoo` when it is called. **Do not** use `Vent.subscribe('test', myFoo.myCallback.bind(myFoo))`, as this causes problems when we try to unsubscribe events.

### Unsubscribing from an event

To unsubscribe, you must use exactly the same call signature you use for `subscribe`, but this time for `unsubscribe`:

    MyEvent.unsubscribe('test', myCallback);

Or, if you subscribed an instance method:

    MyEvent.unsubscribe('test', myFoo.myCallback, myFoo);

### Publishing events

To notify all the subscribers, use the publish method:

    MyEvent.publish('test', 'Hello');

This will call each subscribed callback with a single argument, `"Hello"`. To add more arguments, just put them in the call signature:

    MyEvent.publish('test', 'Hello', 'World');

This will call each subscribed callback with two arguments, `"Hello"` and `"World"`.

### Implementing functionality on your own class

Event.js can implement the pub/sub functionality on any other class using the `implementOn` class method:

    Vent.implementOn(MyClass.prototype);

Then you can use it as before:

    var myInstance = new MyClass();

    myInstance.subscribe(/* ... */);

    // ... and so on

## Some things this fixes

My primary motivation for writing Event.js was that it fixed some problems I was having in some other libraries. When unsubscribing one instance's callback I often found that this would unsubscribe all the instances' callbacks, or fail to recognise the instance/callback combination, because I had to use `callback.bind(obj)`. The way Event.js does things, by having a separate `bind` argument, avoids problems with this, which are related to the way `.bind()` works (it creates a new function, so equality tests always fail).