获取：使用JSON错误对象拒绝Promise

Question

我有一个HTTP API，无论成功还是失败，它都会返回JSON数据。失败示例如下所示：~ ◆ http get http://localhost:5000/api/isbn/2266202022 HTTP/1.1 400 BAD REQUESTContent-Length: 171Content-Type: application/jsonServer: TornadoServer/4.0{    "message": "There was an issue with at least some of the supplied values.",     "payload": {        "isbn": "Could not find match for ISBN."    },     "type": "validation"}我想要在JavaScript代码中实现的是这样的：fetch(url)  .then((resp) => {     if (resp.status >= 200 && resp.status < 300) {       return resp.json();     } else {       // This does not work, since the Promise returned by `json()` is never fulfilled       return Promise.reject(resp.json());     }   })   .catch((error) => {     // Do something with the error object   }

Answer 1

 // This does not work, since the Promise returned by `json()` is never fulfilled

return Promise.reject(resp.json());

好吧，resp.json诺言将得到兑现，只是Promise.reject不等待它，而是立即兑现诺言。

我假设您宁愿执行以下操作：

fetch(url).then((resp) => {

  let json = resp.json(); // there's always a body

  if (resp.status >= 200 && resp.status < 300) {

    return json;

  } else {

    return json.then(Promise.reject.bind(Promise));

  }

})

（或明确写出）

    return json.then(err => {throw err;});