chained-emitter

chained-emitter is a an implementation of the EventEmitter found in Node.js, based on EventEmitter2, but adding the ability to return a promise in an event handler.

npm install chained-emitter
14 downloads in the last week
51 downloads in the last month

ChainedEventEmitter

ChainedEventEmitter is a an implementation of the EventEmitter found in Node.js, based on EventEmitter2, but adding the ability to return a promise in an event handler, so that the next handler waits for the previous to finish before firing. As well, emit() returns a promise that is fulfilled when all of the handlers have fired.

Features

  • Everything from EventEmitter2
  • Event chains

Differences (Non breaking, compatible with existing EventEmitter, EventEmitter2)

  • The constructor takes a configuration object.
    var ChainedEmitter = require('ChainedEmitter').EventEmitter;
    var server = new ChainedEmitter({
      parallel: true, // fire second handler before the first resolves, defaults to false
    });
  • Returning a promise
    var q = require('q')
    server.on('foo.*', function(value1, value2) {
      return q.defer().promise
    });

API

emitter.addListener(event, listener)

emitter.on(event, listener)

Adds a listener to the end of the listeners array for the specified event. If the listener returns a Q promise, the promise returned by emit() will not resolve until the returned promise resolves. If the parallel configuration is false, the next handler will also wait to fire before the returned promise resolves. If you return anything but a promise (including undefined or null), the next action will happen immediately.

    server.on('data', function(value1, value2, value3 /* accepts any number of expected values... */) {
      var me = q.defer();
      return me.promise; // wait for me!
    });
    server.on('data', function(value) {
      return; // don't wait!
    });

Licence

(The MIT License)

Copyright (c) 2011 hij1nx http://www.twitter.com/hij1nx Copyright (c) 2013 hildjj http://www.twitter.com/hildjj

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

npm loves you