crear explorador web reactjs code example

Example: añadir react a node project

import React, { Component } from 'react';import logo from './logo.svg';import './App.css';class App extends Component {  constructor(){    super()    this.state = {      numero: 0    }    this.handleRandom = this.handleRandom.bind(this)    this.handleRandomType = this.handleRandomType.bind(this)  }  componentDidMount() {    this.handleRandom();  }callApi = async (a) => {    let response;    if(a===undefined){      response = await fetch(`/api/random`);    } else{      response = await fetch(`/api/random/${a}`);    }    const body = await response.json();    if (response.status !== 200) throw Error(body.message);    return body;};handleRandom(){    this.callApi()    .then(res => {      let numero = res.number;      this.setState({ numero: numero })    })    .catch(err => console.log(err));  }handleRandomType(type){    this.callApi(type)    .then(res => {      let numero = res.number;      this.setState({ numero: numero })    })    .catch(err => console.log(err));  }render() {    return (      <div className="App">        <header className="App-header">          <img src={logo} className="App-logo" alt="logo" />          <h1 className="App-title">Números Random</h1>        </header>        <p className="App-intro">        Número random: {this.state.numero}        </p>        <hr/>        <p>          <button onClick={this.handleRandom}>Número Random</button>          <button onClick={ ()=> this.handleRandomType("even")}>Número Random Par</button>          <button onClick={ ()=> this.handleRandomType("odd")}>Número Random Impar</button>        </p>      </div>    );  }}export default App;