http请求

方式一

postData('http://example.com/answer', {answer: 42})
  .then(data => console.log(data)) // JSON from `response.json()` call
  .catch(error => console.error(error))

function postData(url, data) {
  // Default options are marked with *
  return fetch(url, {
    body: JSON.stringify(data), // must match 'Content-Type' header
    cache: 'no-cache', // *default, no-cache, reload, force-cache, only-if-cached
    credentials: 'same-origin', // include, same-origin, *omit
    headers: {
      'user-agent': 'Mozilla/4.0 MDN Example',
      'content-type': 'application/json'
    },
    method: 'POST', // *GET, POST, PUT, DELETE, etc.
    mode: 'cors', // no-cors, cors, *same-origin
    redirect: 'follow', // manual, *follow, error
    referrer: 'no-referrer', // *client, no-referrer
  })
  .then(response => response.json()) // parses response to JSON
}

方式二

loadData2(){

    let url = `https://api.github.com/search/repositories?q=${this.searchKey}`;
    fetch(url)
      .then(response => {

        console.log("response: " + response);
        if(response.ok){
          return response.text();
        }
        throw new Error ("服务没有响应");

      })
      .then(responseText => {
        this.setState({

          showText:responseText
        })
      })
    
      .catch(e => {
        alert(e.toString());
         this.setState({
          showText:e.toString
         })
      })

  }