Just a very brief introduction to Bacon.js

baconjs-playground.js

// Bacon.js playground

// This is how event handling is done in jQuery
$('#btn').on('click', function(evt) {
  alert("I was clicked!");
});

// This is how you do it in Bacon.js
var click = $('#btn').asEventStream('click');
click.onValue(function(evt) {
  alert("I was clicked with Bacon!");
});

// LOL! THAT'S MUCH MORE CODE TO WRITE!!!
// Yeah, in this case you're right. But Bacon has more nice stuff

// How about mapping functions
var likeButton = $('#like-btn').asEventStream('click');
likeButton
  .map(1)
  .onValue(function(val) {
    alert("You have " + val + " more like!");
  })
;
// by the way: .map(1) is short for .map(function(inp) { ...; return 1; })

// Oh, you can have filters, too!
var password = $('#secret-password-input').asEventStream('blur');
password
  .map(function(evt) {
    return evt.target.value
  })
  .filter(function(val) {
    return val == 's3cr3t';
  })
  .onValue(function() {
    // This will only trigger, if filter function returns TRUE
    alert("OMG! YOU DID IT.");
  })
;

// You can merge streams!
var plusOne = $('#plus-btn').asEventStream('click').map(1);
var minusOne = $('#minus-btn').asEventStream('click').map(-1);

Bacon
  .merge(plusOne, minusOne)
  .onValue(function(val) {
    alert("You clicked: " + val);
  })
;

// Bacon.js also know "Properties". These are kind like event streams, but with a concept of a current value
var prop = Bacon.property(42);

// You can make an event stream a property with the .toProperty() method. Its argument is the property's initial value
var accept = $('#accept-toc-checkbox')
  .asEventStream('click')
  .map(function(evt) {
    return !!evt.target.value;
  })
  .toProperty(false)
;

accept.onValue(function(val) {
  alert('You did ' + (!val ? 'not ' : '') + 'accept the toc');
});
// This will promptly yield 'You did not accept the toc'

// We can do better! Use a property's value to enable or disable a button
accept
  .not() // .not() reverses the value
  .assign($('#signup-btn'), 'attr', 'disabled')
;

// Or how about combining streams?
var over18 = $('#over18-checkbox')
  .asEventStream('click')
  .map(function(evt) {
    return !!evt.target.value;
  })
  .toProperty(false)
;

Bacon
  .combineWith(function(v1, v2) { return v1&&v2; }, accept, over18)
  .not()
  .assign($('#signup-btn'), 'attr', 'disabled')
;
// This will only enable the signup button, if you accepted the toc and you're over 18

// There's a short variant, too
accept.and(over18).not().assign($('#signup-btn'), 'attr', 'disabled');

// Want a real word example?
// See: http://jsfiddle.net/b00gizm/nby9P/

var valueFromEvt = function(evt) {
  return evt.target.value;
};
    
var username = $('input[name=username]')
  .asEventStream('blur')  // on blur
  .map(valueFromEvt)      // apply 'valueFromEvent'
  .toProperty('')         // set initial value to ''
;
    
var email = $('input[name=email]')
  .asEventStream('blur')
  .map(valueFromEvt)
  .toProperty('')
;
    
var bothNotEmpty = function(v1, v2) {
  return !!v1 && !!v2;
}
    
Bacon
  .combineWith(bothNotEmpty, username, email)
  .not()
  .assign($('#signup-btn'), 'attr', 'disabled')
;