Question

我正在尝试使此代码同步，但是由于某种原因async / await无法正常工作。我在具有两个不同模块的React-native中工作。我想查看我在googleMaps中的地理位置，但是因为异步的东西，这让我出错了。

应用程序是根组件，它导入了getLocalitation函数。

export default class App extends Component {
    Appmetod = async () => {
        const resp = await getLocalitation();
        console.log('Appmetod: latitud: ' + resp.latitude);
        Linking.openURL(`http://www.google.com/maps/place/-33.317597,-71.405500`);
    }
    render() {
        return (
            <View style={styles.container}>
              <Button title="Click me" onPress={this.Appmetod } />
            </View>
        );
    }
}

const getLocalitation = () =>{
    console.log('DENTRO DE GetLocalitaion');

    const geoOptions={
        enableHighAccuracy: true,
        timeOut: 10000
    };

    const coordenates =  navigator.geolocation.getCurrentPosition( geoSucces,goFailure, geoOptions);
    console.log('DESPUES DE COORDENATES');

    return coordenates;
} 

const geoSucces = (position) => {
    console.log('DENTRO DE GEOSUCCEES');

    const latitude = position.coords.latitude;
    const longitude = position.coords.longitude;

    const coordenates={
        latitude: latitude,
        longitude: longitude
    };

    console.log('COORDENATES: ' + coordenates.latitude);
    return coordenates;
}

const goFailure = (err) => {
    console.log('Error en al geolocalizar: ' + err);
    return null;
}

输出：

C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\Utilities\infoLog.js:16 Running application "geolocation" with appParams: {"rootTag":161}. __DEV__ === true, development-level warning are ON, performance optimizations are OFF
C:\Users\jnunez\React-Native\Proyects\geolocation\src\getLocalitation.js:2 DENTRO DE GetLocalitaion
C:\Users\jnunez\React-Native\Proyects\geolocation\src\getLocalitation.js:10 DESPUES DE COORDENATES
C:\Users\jnunez\React-Native\Proyects\geolocation\src\getLocalitation.js:16 DENTRO DE GEOSUCCEES
C:\Users\jnunez\React-Native\Proyects\geolocation\src\getLocalitation.js:26 COORDENATES: -32.92098393
C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\YellowBox\YellowBox.js:67 Possible Unhandled Promise Rejection (id: 0):
TypeError: Cannot read property 'latitude' of undefined
TypeError: Cannot read property 'latitude' of undefined
    at _callee$ (blob:http://localhost:8081/19d9ce97-42d2-4939-91b8-160b264c9c79:1895:58)
    at tryCatch (blob:http://localhost:8081/19d9ce97-42d2-4939-91b8-160b264c9c79:41538:19)
    at Generator.invoke [as _invoke] (blob:http://localhost:8081/19d9ce97-42d2-4939-91b8-160b264c9c79:41713:24)
    at Generator.prototype.<computed> [as next] (blob:http://localhost:8081/19d9ce97-42d2-4939-91b8-160b264c9c79:41581:23)
    at tryCatch (blob:http://localhost:8081/19d9ce97-42d2-4939-91b8-160b264c9c79:41538:19)
    at invoke (blob:http://localhost:8081/19d9ce97-42d2-4939-91b8-160b264c9c79:41614:22)
    at blob:http://localhost:8081/19d9ce97-42d2-4939-91b8-160b264c9c79:41624:15
    at tryCallOne (blob:http://localhost:8081/19d9ce97-42d2-4939-91b8-160b264c9c79:45254:14)
    at blob:http://localhost:8081/19d9ce97-42d2-4939-91b8-160b264c9c79:45355:17
    at blob:http://localhost:8081/19d9ce97-42d2-4939-91b8-160b264c9c79:46233:21
console.warn @ C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\YellowBox\YellowBox.js:67
onUnhandled @ C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\Promise.js:45
onUnhandled @ C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\promise\setimmediate\rejection-tracking.js:71
(anonymous) @ C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\Core\Timers\JSTimers.js:256
_callTimer @ C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\Core\Timers\JSTimers.js:152
callTimers @ C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\Core\Timers\JSTimers.js:414
__callFunction @ C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:366
(anonymous) @ C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:106
__guard @ C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:314
callFunctionReturnFlushedQueue @ C:\Users\jnunez\React-Native\Proyects\geolocation\node_modules\react-native\Libraries\BatchedBridge\MessageQueue.js:105
(anonymous) @ debuggerWorker.js:80

Answer 1

await / async不会阻止代码异步。

它们是使您可以通过管理承诺来编写非异步样式代码的工具。

您只能await个承诺。 getLocalitation不返回承诺。

请参见How do I convert an existing callback API to promises?，以获得对navigator.geolocation.getCurrentPosition的承诺。

Answer 2

这是因为您使用的 await 关键字的功能不是 async

const resp = await getLocalitation();

您可以在定义 getLocation 时将 async 放在()之前，也可以只将{strong> await 从{{1 }}，因为您不需要将 await 用于不会返回承诺的内容。

如果您想使const resp = await getLocalitation()异步，您可以这样做

getLocalitation

如何使此功能与Asyn / await同步

2 个答案: