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Advanced mediator library


Lasso is small library that helps to decouple your application into separated units of code that don't depend on each other. Library implements mediator pattern with advanced broadcast / listen (publish / subscribe) system.

How to use?

Basic usage

//subscribe callback for 'hello-event' event 
lasso.listen("hello-event", function(name) {
    alert("Hello, " + name + "!");
//fire event and pass additional parameter 
lasso.broadcast("hello-event", "Lasso");
//the same for 'publish' and 'subscribe' methods 
lasso.subscribe("the-same-for-subscribe", function(name) {
    alert("Hello, " + name + "!");
lasso.broadcast("the-same-for-subscribe", "Lasso");

Subscribe callback for few events

lasso.listen("event1, event2", function() {
lasso.broadcast("event1, event2");
//as objects 
    "event1": function(obj) {
        alert("Handler for event1, with " +;
    "event2": function(arg1, arg2, arg3) {
        alert("Handler for event2, with " + arguments.join(","));
    //fire event1 and pass object 
    "event1": {
        foo: "bar"
    //pass array with numbers 
    "event2": [1,2,3]

Get listeners

//Create 3 handlers for the same event 
lasso.listen("firstEvent", function() {
    return 1;
lasso.listen("firstEvent", function() {
    return 2;
lasso.listen("firstEvent", function() {
    return 3;
//add another event handler 
lasso.listen("anotherEvent", function() {
    return "i am not like others!";
//Returns an array with method handlers for 'firstEvent' 
var firstEventHandlers = lasso.listeners("firstEvent");
firstEventHandlers.length == 3 ; // true 
//without params returns all methods in mediator 
var allEvents =lasso.listeners();
allEvents.length == 4 ; // true 

Clear subscribers

//removes all events, clears mediator 
//removes all subscribers for specified event 
lasso.clear("eventName"); //or 
lasso.clear("eventName, otherEvent");
//removes specified handler 
function handler() {
    return "i am method!";
lasso.clear("eventName", handler);

Subscribe for events made from specific object.

var broadcaster = {
    name: "Max"
lasso.from(broadcaster).listen("event", function() {
    alert("I am listening only broadcaster object!");
lasso.broadcast("event"); // wont work 
lasso.from(broadcaster).broadcast("event"); //works perfect 

Use with favorite library

$.lasso.listen("foo", function(name) {
    alert("Hello, " + name + "!");
$.lasso.broadcast("foo", "bar");
Backbone.Mediator.subscribe('foo', function() {
    alert("Just works!")
//or integrate into any library or object 
var library = {
    //the best code ever 
lasso.into(library); //or lasso.integrate(library) 
library.listen('foo-event', function(bar) {
library.broadcast('foo-event', "bar");


> npm install lasso-js

License notes (MIT License)

Copyright (c) 2012 Max Podriezov

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.