App.js

import React from "react";
import Echo from "./components/Echo";
import Header from "./components/Header";
import EchoService from "./services/Echo";
import "./App.css";

class App extends React.Component {
  constructor() {
    super();

    this.refreshInterval = 1000;
    this.useMockData = false;

    this.state = {
      echoResult: {},
      nrRefresh: 0,
    };
  }

  componentDidMount() {
    setInterval(this.loadData, this.refreshInterval);
  }

  loadData = () => {
    const echoService = EchoService(this.useMockData);
    const nrRefresh = this.state.nrRefresh + 1;

    echoService
      .fetch("/api/echo")
      .then(data => this.setState({ echoResult: data, nrRefresh: nrRefresh }));
  };

  render() {
    return (
      <div className="App">
        <Header />
        <Echo
          result={this.state.echoResult}
          refreshInterval={this.refreshInterval}
          nrRefresh={this.state.nrRefresh}
        />
      </div>
    );
  }
}

export default App;