Lodash: is it possible to use map with async functions?

Question

Consider this code

const response  = await fetch('<my url>'); const responseJson = await response.json(); responseJson =  _.sortBy(responseJson, "number");  responseJson[0] = await addEnabledProperty(responseJson[0]); 

What addEnabledProperty does is to extend the object adding an enabled property, but this is not important. The function itself works well

async function addEnabledProperty (channel){      const channelId = channel.id;     const stored_status = await AsyncStorage.getItem(`ChannelIsEnabled:${channelId}`);     let boolean_status = false;     if (stored_status == null) {         boolean_status = true;     } else {         boolean_status = (stored_status == 'true');     }      return _.extend({}, channel, { enabled: boolean_status }); } 

Is there a way to use _.map (or another system), to loop trough entire responseJson array to use addEnabledProperty against each element?

I tried:

responseJson = _.map(responseJson,  function(channel) {             return addEnabledProperty(channell);         }); 

But it's not using async so it freeze the app.

I tried:

responseJson = _.map(responseJson,  function(channel) {             return await addEnabledProperty(chanell);         }); 

But i got a js error (about the row return await addEnabledProperty(chanell);)

await is a reserved word

Then tried

responseJson = _.map(responseJson, async function(channel) {             return await addEnabledProperty(channell);         }); 

But I got an array of Promises... and I don't understand why...

What else!??

EDIT: I understand your complains about I didn't specify that addEnabledProperty() returns a Promise, but, really, I didn't know it. In fact, I wrote "I got an array of Promises... and I don't understand why "

Answer 1

To process your response jsons in parallel you may use Promise.all:

const responseJson = await response.json(); responseJson = _.sortBy(responseJson, "number");  let result = await Promise.all(_.map(responseJson, async (json) =>    await addEnabledProperty(json)) ); 

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Since addEnabledProperty method is async, the following also should work (per @CRice):

let result = await Promise.all(_.map(responseJson, addEnabledProperty));