等待异步完成（等待）

Question

I am trying to get my head around with async/await

I am using https://github.com/sunnylqm/react-native-storage for my project in react-native.

I am using async storage to store few critical information such as selected user locale, I need to retrieve this value before screen is rendered to display screen based on selected locale.

I have tried implementing several helper functions, it works with callback, what I need is to return the value instead of callback and wait until the value is fetched. Below are few examples I tried.

// 1
_selectedLocale = async () => {
  try {
    const value = await global.storage.load({key: 'selectedLocale'});
    return value
   } catch (error) {
     console.log(value)
   }
}
var selectedLocale = _selectedLocale();

// 2
export async function _selectedLocale() {
  return storage.load({key: 'selectedLocale'});
}
var selectedLocale = _selectedLocale();
// 3
export function selectedLocale(callback) {
  storage.load({key: 'selectedLocale'}).catch(e => {
    callback(RNLanguages.language);
  }).then(function(locale) {
    callback(locale);
  });
}

This is not working, I am looking to

1. Implement a helper function to retrieve a value based on key
2. Wait until the value is retrieved (sync)

Can someone point me to right direction

Thanks

UPDATE1:

Here is how I am using the callback

selectedLocale(function(locale) {
  global.layoutIsRTL = 'ar' == locale;
  ReactNative.I18nManager.allowRTL(true);
  global.i18n.locale = locale
});

UPDATE2:

It seems someone has already done this, here is the reference https://github.com/sunnylqm/react-native-storage/issues/206 unfortunately I am having hard time understanding it.

Answer 1

async implicitly returns a promise, so you need to await the function call as well if you want the value there:

var selectedLocale = await _selectedLocale();

but you can only do that inside of another async function