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    DefinitelyTyped icon, indicating that this package has TypeScript declarations provided by the separate @types/event-emitter package

    0.3.5 • Public • Published


    Environment agnostic event emitter


    $ npm install event-emitter

    To port it to Browser or any other (non CJS) environment, use your favorite CJS bundler. No favorite yet? Try: Browserify, Webmake or Webpack


    var ee = require('event-emitter');
    var MyClass = function () { /* .. */ };
    ee(MyClass.prototype); // All instances of MyClass will expose event-emitter interface
    var emitter = new MyClass(), listener;
    emitter.on('test', listener = function (args) {
      // … react to 'test' event
    emitter.once('test', function (args) {
      // … react to first 'test' event (invoked only once!)
    emitter.emit('test', arg1, arg2/*…args*/); // Two above listeners invoked
    emitter.emit('test', arg1, arg2/*…args*/); // Only first listener invoked
    emitter.off('test', listener);              // Removed first listener
    emitter.emit('test', arg1, arg2/*…args*/); // No listeners invoked

    Additional utilities

    allOff(obj) (event-emitter/all-off)

    Removes all listeners from given event emitter object

    hasListeners(obj[, name]) (event-emitter/has-listeners)

    Whether object has some listeners attached to the object. When name is provided, it checks listeners for specific event name

    var emitter = ee();
    var hasListeners = require('event-emitter/has-listeners');
    var listener = function () {};
    hasListeners(emitter); // false
    emitter.on('foo', listener);
    hasListeners(emitter); // true
    hasListeners(emitter, 'foo'); // true
    hasListeners(emitter, 'bar'); // false
    emitter.off('foo', listener);
    hasListeners(emitter, 'foo'); // false

    pipe(source, target[, emitMethodName]) (event-emitter/pipe)

    Pipes all events from source emitter onto target emitter (all events from source emitter will be emitted also on target emitter, but not other way).
    Returns pipe object which exposes pipe.close function. Invoke it to close configured pipe.
    It works internally by redefinition of emit method, if in your interface this method is referenced differently, provide its name (or symbol) with third argument.

    unify(emitter1, emitter2) (event-emitter/unify)

    Unifies event handling for two objects. Events emitted on emitter1 would be also emitted on emitter2, and other way back.
    Non reversible.

    var eeUnify = require('event-emitter/unify');
    var emitter1 = ee(), listener1, listener3;
    var emitter2 = ee(), listener2, listener4;
    emitter1.on('test', listener1 = function () { });
    emitter2.on('test', listener2 = function () { });
    emitter1.emit('test'); // Invoked listener1
    emitter2.emit('test'); // Invoked listener2
    var unify = eeUnify(emitter1, emitter2);
    emitter1.emit('test'); // Invoked listener1 and listener2
    emitter2.emit('test'); // Invoked listener1 and listener2
    emitter1.on('test', listener3 = function () { });
    emitter2.on('test', listener4 = function () { });
    emitter1.emit('test'); // Invoked listener1, listener2, listener3 and listener4
    emitter2.emit('test'); // Invoked listener1, listener2, listener3 and listener4

    Tests Build Status

    $ npm test


    npm i event-emitter

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