问反应API获取失败

EN

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

class App extends Component {

constructor(props) {
  super(props);
  this.state = {
    isLoaded: false,
    items: []
  }
}

componentDidMount() {


  const myHeaders = new Headers();

  myHeaders.append('x-api-key', 'KEY_HERE');
  myHeaders.append('Content-Type', 'application/x-www-form-urlencoded');
  myHeaders.append('cache-control', 'no-cache')

  fetch('URL_HERE', {
    method: 'GET',
    headers: myHeaders,
    async: true,
  })
  .then(res => res.json())
  .then(json => {
    this.setState({
      isLoaded: true,
      items: json,
    })
  });
}

  render() {
  var{isLoaded, items} = this.state;
  if(!isLoaded) {
    return <div>Loading...</div>;
  }

  else{
   return (
     <div className="App">
       <ul>
         {items.map(item => (
           <li key={item.id}>
             Name: {item.name} | Id:{item.id}
           </li>
         ))};
       </ul>
     </div>
   );
  }
}