react-context.js

import React, {Component, PureComponent, createContext} from 'react';

const Context = createContext();

class User {
  constructor(getState, rootUpdater) {
    this._getState = getState;
    this._rootUpdater = rootUpdater;

    this.name = '';
    this.surname = '';
  }

  _setValue = (value = {}) => {
    this._rootUpdater({
      user: {
        setName: this.setName,
        setSurname: this.setSurname,
        ...this._getState().user,
        ...value
      }
    });
  };

  setName = (name = '') => {
    this._setValue({name});
  }

  setSurname = (surname = '') => {
    this._setValue({surname});
  }

}

class Store extends Component {
  constructor(props) {
    super(props);
    this.rootUpdater = (data = {}) => {
      this.setState({
        ...this.state,
        ...data
      })
    };

    this.getState = () => {
      return this.state;
    };

    const user = new User(this.getState, this.rootUpdater);
    this.state = {user};
  }

  render() {
    return (
      <Context.Provider value={this.state}>
        {this.props.children}
      </Context.Provider>
    );
  }
}

function Layout() {
  return (
    <div>
      <Title />
      <Input />
    </div>
  );
}


class Title extends PureComponent {
  static contextType = Context;

  render() {
    return (
      <div>
        <h3>
          name {this.context.user.name}
        </h3>
        <h3>
          surname {this.context.user.surname}
        </h3>
      </div>
    );
  }
}


class Input extends PureComponent {
  static contextType = Context;
  constructor(props) {
    super(props);
    this.nameInput = React.createRef();
    this.surnameInput = React.createRef();
  }

  setName = (e) => {
    this.context.user.setName(e.target.value);
  }

  setSurname = (e) => {
    this.context.user.setSurname(e.target.value);
  }

  render() {
    return (
      <div>
        <div>

          <p>change name </p>
          <input ref={this.nameInput} onChange={this.setName} />
        </div>
        <div>
          <p>change name </p>
          <input ref={this.surnameInput} onChange={this.setSurname} />
        </div>
      </div>
    );
  }
}

export function App() {
  return (
    <Store>
      <Layout />
    </Store>
  );
}