localMobxExample.jsx

import React, { Component } from 'react';
import { action, observable }  from 'mobx';
import { observer } from 'mobx-react';

@observer
export default class User extends Component {
    @observable user = {
        firstName: 'john',
        lastName: 'lennon',
        status: 'alive'
    };

    @action updateUserStatus(newStatus) {
        this.user.status = newStatus
    }

    render() {
        const { firstName, lastName, status } = this;

        return (
            <p>{firstName} {lastName} - {status}</p>
        );
    }
}