node-listener-collection

This library extends the standard event mechanism with ability to wait until all asynchronous events are processed.

npm install listener-collection

Callback based

var ListenerCollection = require("listener-collection");

var liseners = new ListenerCollection();

listeners.add("listener1", function(param1, param2, next) {
   setTimeout(function() {
     console.log("listener");  
     next();
   }, 100);
});

listeners.add("listener2", function(param1, param2, next) {
   setTimeout(function() {
     console.log("listener2");  
     next();
   }, 200);
});

listeners.fire("A", "B", function() {
  console.log("both listeners are processed now");
});

Promise based

var ListenerCollection = require("listener-collection");

var liseners = new ListenerCollection();

listeners.add("a name", function(param1, param2) {
   console.log("listener catch");  
   return promise;   
});

listeners.fire("A", "B").then(function() {
  console.log("everything is done");
});

Listener context

listeners.add("a name", context, function() {
   //this runs bound to context
});

Listener position

Listeners are executed one by one in order they were added. If you want to add a listener to a particular position you can use insert and specify the condition when the listener should be invoked.

listeners.add("listener1", function() { ... });
listeners.add("listener2", function() { ... });
listeners.insert({ after: "listener1" }, "listener3", function() { ... });

Alternatively you can also use before instead or together with after.

Removing listener

listeners.add("test", function () { });
listeners.remove("test");

Hooks

listeners.post(function() {
  console.log("this runs after the listeners are invoked");
});

listeners.pre(function() {
  console.log("this runs before the listeners are invoked");
});

listeners.postFail(function(err) {
  console.log("this runs after the listeners are invoked when one of the listeners fails");
});

License

MIT