Observable.js is a tiny library (gzipped less then 1.4KB) that makes knockout's gorgeous observables available, without the bloat of the whole knockout.js framework.

Works just like Knockout

It supports ko.observable, ko.subscribable and ko.computed. Designed for maximum compatibility these run successfully against knockout's own unit test specification.

var knockout = ko.observable("Knockout.js");
var rocks    = ko.computed(function(){
    console.log( knockout() + " rocks!" );
});
// Prints "Knockout.js rocks!"

knockout("Observable.js");
// Prints "Observable.js rocks!"

Has support for Node.js

This also works great on node. Install it with npm install ko-observable and you can use it just like in the browser:

var ko = require('ko-observable');

I developed this to embed observables into my own integration testing framework - surely you can imagine other places where some observables might be useful 😉