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Minimal but versatile JavaScript pub/sub working everywhere


A minimal but versatile JavaScript pub/sub module, very similar to Node's EventEmitter, but more flexible and working also in the browser. It can be required with CommonJS, AMD and standard browser <script> tag. Coffeescript version provided too.

var es = new EventSpitter;
// Attach a listener to an event 'foo' 
es.on("foo", function( evt, arg1, arg2 ) {
  console.log( "I was triggered by event " + evt );
  console.log( "I was passed additional arguments " + arg1 + " and " + arg2 );
// Attach a listener using a regular expression 
es.on(/^f/, function() {
  console.log("I am listening to any event starting with 'f'");
// Emit an event 'foo' passing additional arguments 123 and "xyz" 
es.emit("foo", 123, "xyz");
// Most methods are chainable 
es.on("bar", function() {

Altough EventSpitter and Node's EventEmitter are a lot similar, EventSpitter is not meant as a drop-in replacement, as the API is not identical. Some notable differences are that EventSpitter:

  • is meant to work also in the browser

  • lets you match events using regular expressions

  • passes the name of the event as the first argument to callbacks

  • returns this in most method, enabling chainability

  • does not treat the 'error' event in any special way

Adds the callback cbk as a listener for any event matched by matcher, which can be a String or a RegExp.

Works like on, except that it only subscribes for the event the first time it is emitted, and then immediately unsubscribes.

Executes each listener for the event, passing it the event name and each additional argument (like arg1, arg2, etc.)

Returns an array of all the callbacks which are executed when event is emitted.

If called with no arguments, removes every event listener. If called only with an event matcher (String or RegExp), it removes all listeners listening to that matcher. If called passing a matcher and a callback, it removes only that one callback from the listeners listening to that matcher.


  • 0.0.4 - Available as a Bower component

  • 0.0.3 - Fix bugs with RegExp listeners

  • 0.0.2 - Fix bug with off when there are no subscriptions

  • 0.0.1 - Fix bug with listeners method modifying the array of subscriptions

  • 0.0.0 - First alpha release