app.js

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

class App extends Component {

  constructor(props) {
    super(props);
    this.state = { value: ''};
    this.handleClick = this.handleClick.bind(this);
  }

  handleChange(event) {
    this.setState({ value: event.target.value });
  }

  handleClick() {
    fetch(`http://localhost:3000/posts/${this.state.value}`)
      .then(function (response) {
        return response.text()
      }).then(function (body) {
        document.body.innerHTML = body
      })
  }

  render() {
    return (
      <div className="App">
        <div className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h2>Welcome to React</h2>
        </div>
        <p className="App-intro">
          <input type="text" value={this.state.value} onChange={this.handleChange.bind(this)} />
          <button onClick={this.handleClick}>CLICK!</button>
          To get started, edit <code>src/App.js</code> and save to reload.
        </p>
      </div>
    );
  }
}

export default App;