closure-example

index.js

import React from "react";
import ReactDOM from "react-dom";

class App extends React.Component {
  componentDidMount() {
    const Closure = (() => {
      let _value = 0;

      return {
        print: () => _value,

        plus: () => {
          _value += 1;
        },
        minus: () => {
          _value -= 1;
        }
      };
    })();

    console.log(Closure.print()); // 0
    Closure.plus();
    console.log(Closure.print()); // 1
  }

  render() {
    return <div className="App" />;
  }
}

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);