MobX-store.js

class ObservableTodoStore {
    @observable todos = [];
    @observable pendingRequests = 0;
​
    constructor() {
        mobx.autorun(() => console.log(this.report));
    }
​
    @computed get completedTodosCount() {
        return this.todos.filter(
            todo => todo.completed === true
        ).length;
    }
​
    @computed get report() {
        if (this.todos.length === 0)
            return "<none>";
        return `Next todo: "${this.todos[0].task}". ` +
            `Progress: ${this.completedTodosCount}/${this.todos.length}`;
    }
​   
    @action
    addTodo(task) {
        this.todos.push({
            task: task,
            completed: false,
            assignee: null
        });
    }
}
​
​
const observableTodoStore = new ObservableTodoStore();