import React, { Component } from 'react'; class App extends Component { constructor(props) { super(props); this.state = { age: 0, }; } // this.checkAge is passed as the callback to setState updateAge = (value) => { this.setState({ age: value}, this.checkAge); }; checkAge = () => { const { age } = this.state; if (age !== 0 && age >= 21) { // Make API call to /beer } else { // Throw error 404, beer not found } }; render() { const { age } = this.state; return ( <div> <p>Drinking Age Checker</p> <input type="number" value={age} onChange={e => this.updateAge(e.target.value)} /> </div> ); } } export default App;