Object.observe is dead. Long live Mobservable.observe

autorun.js

// JSBin: http://jsbin.com/xoyehi/edit?js,console
import {observable, autorun} from "mobx";

const todos = observable([{
    title: "Find napkin",
    completed: false
}]);

autorun(() =>
    console.log(todos
        .filter(todo => !todo.completed)
        .map(todo => todo.title)
        .join(", "))
);
// Prints: 'Find napkin'

todos[1] = {
    title: "Sneeze",
    completed: false
};
// Prints: 'Find napkin, Sneeze'

todos[0].completed = true;
// Prints: 'Sneeze'

todos[1].title = 'Ha.. ha... ha....'
// Prints: 'Ha.. ha... ha.... '

todos[0].title = "Foobar";
// (doesn't print)