Updating state in React with a form input box example

gistfile1.txt

import React, { Component } from 'react';
import './App.css';

export default class ToDoList extends Component {
  constructor(props) {
    super(props);

    this.state = {
      userInput: '',
      list: []
    }
  }

  changeUserInput(input) {
    this.setState({
      userInput: input
    });
  }

  render() {
    return (
      <div className="to-do-list-main">
        <input
          onChange={ (e) => this.changeUserInput(e.target.value)}
          value={this.state.userInput}
          type="text"
        />
        <button>Press Me</button>
      </div>
    );
  }
}