javascript - using _.map and async.map together -

i'm using both _.map , async.map in node portion of application i'm working on. i'm running confusion while using these libraries together.

i have array of arrays called results looks this:

[[1, 2, 3], [2, 4, 6], [1, 3, 5]] 

i use _.map access each inner array, , async.map make api call each value within each of these inner arrays. use results of api call replace each integer within inner arrays object.

so @ end array of arrays of integers instead array of arrays of objects based on api call results.

[[{id: 1, email: 'test@example.com', state: 'active'}], ...] 

this current code have, , believe i'm on right path. first console.log gives me object i'm aiming for, second returns integer:

_.map(results, function(result) {   async.map(result, function(user, callback) {     db.users.getbyid(user, function(err, userdetails) {       if (err) {         callback(null, null);       } else {         user = _.pick(userdetails, 'id', 'email', 'state');         console.log(user);       }     });     console.log(user);   }) }); 

from docs:

_.map(results, function(result) {   async.map(result, function(user, callback) {     db.users.getbyid(user, function(err, userdetails) {       callback(err, _.pick(userdetails, 'id', 'email', 'state'));     });   }, function(err, users){     // here have populated array of (arrays of) users   }) }); 

but you'll find promise.all more expressive in regard.