Javascript Promise resolve上JSON输入意外结束

我从OpenWeatherAPI请求天气数据，每次我的承诺得到解决并执行JSON.pase（daat）时，我都会得到“error SyntaxError:Object.parse（）处JSON输入的意外结束” 我得到的JSON如下所示：

{
 "coord":{"lon":24.94,"lat":60.17},
 "weather":[{"id":741,"main":"Fog","description":"fog","icon":"50n"}],
 "base":"stations",
 "main":{"temp":273.15,"pressure":994,"humidity":94,"temp_min":273.15,"temp_max":273.15},
 "visibility":500,
 "wind":{"speed":1.5},
 "clouds":{"all":90},
 "dt":1489872000,
 "sys":{"type":1,"id":5019,"message":0.4444,"country":"FI","sunrise":1489811101,"sunset":1489854738},
 "id":658225,
 "name":"Helsinki",
 "cod":200
}

httpRequestWeather(weatherNowHTTPQuery + "Helsinki" + weatherAPIToken).then(function(data){

    let myData = JSON.parse(data);
     //always returns error when trying to do JSON.parse()
    self.setState({
        weatherConditions: "Weather is here!"
     });
    self.setState({
        //always returns error when trying to do JSON.parse()
        weatherObj: JSON.parse(data)
    });

}).catch(function(err){
    console.log("error", err);
    self.setState({
        weatherConditions: "Buy"
     });

它似乎是完全有效的，至少从普通的JS文件中请求它。 尽管来自我的React应用程序（请参阅问题：） 我的代码如下所示：

{
 "coord":{"lon":24.94,"lat":60.17},
 "weather":[{"id":741,"main":"Fog","description":"fog","icon":"50n"}],
 "base":"stations",
 "main":{"temp":273.15,"pressure":994,"humidity":94,"temp_min":273.15,"temp_max":273.15},
 "visibility":500,
 "wind":{"speed":1.5},
 "clouds":{"all":90},
 "dt":1489872000,
 "sys":{"type":1,"id":5019,"message":0.4444,"country":"FI","sunrise":1489811101,"sunset":1489854738},
 "id":658225,
 "name":"Helsinki",
 "cod":200
}

httpRequestWeather(weatherNowHTTPQuery + "Helsinki" + weatherAPIToken).then(function(data){

    let myData = JSON.parse(data);
     //always returns error when trying to do JSON.parse()
    self.setState({
        weatherConditions: "Weather is here!"
     });
    self.setState({
        //always returns error when trying to do JSON.parse()
        weatherObj: JSON.parse(data)
    });

}).catch(function(err){
    console.log("error", err);
    self.setState({
        weatherConditions: "Buy"
     });

但是，在http请求内部，数据的解析非常好：

function httpRequestWeather(url) {
    return new Promise(function(resolve, reject) {
        var weatherRequest = new XMLHttpRequest();
        weatherRequest.open("GET", url, true);
        weatherRequest.onreadystatechange = function() {
            if ( this.status === 200) {
                console.log("request finished and response is ready");
                console.log(this.response);
                //this works perfectly fine

                self.setState({
                    weatherConditions: this.response
                 });
                resolve(this.response);
            } else{
                reject(new Error("no weather data"));
            }
          };
        weatherRequest.send();
    });
  }

---

您没有检查

readyState

<代码>状态在

readyState

为4之前可以是

200

。请记住，您会收到对

onreadystatechange

处理程序的多个回调，但承诺只能解决一次

因此，改变：

if ( this.status === 200) {
    // ...success...
} else {
    // ...error...
}

到

以下是您在JSFIDLE上的原始版本（稍作修改以使用JSFIDLE的JSON echo内容），显示了错误：

---

下面是一个上面的更新，显示它正在工作：

您是否尝试了

weatherObj:myData

替代？不工作，仍然存在错误SyntaxError:在Weather.js:45的Object.parse（）处JSON输入意外结束浏览器中的URL API调用是否正确呈现JSON响应？数据已经被解析，只需设置

weatherObj:data

而不是解析它。@RandomUser我想你是对的。谢谢！这有帮助！