Agfdhyk

I have this code:

 _getSupport()

.then((data) => {                   

    _getSupport(data[0])

        .then(() => _getSupport(data[1])    

})

.catch(e => {

      console.log(e);

});

_getSupport return a Promise.
My goal is to call again _getSupport on values returned the first time.
So I tought:

_getSupport()

.then((data) => {       

    let a = ;

    data.forEach(element => {

        a[element] = _getSupport(element)   

      });

      Promise.all(a).then().catch(e => {

      });

 })

 .catch( e => {console.log(e)})

But this does not work, the code always goes to the last catch.

UPDATE

The getSupport() is of this form

function _getSupport(param = {}) {       



    return new Promise((resolve, reject) => {           

        remoteClient.sendRequest(request, function (data) {             

            resolve(data);

        });

    });

}    

Here lies the problem

let a = ;

data.forEach(element => {

  a[element] = _getSupport(element)   

});

Since the data can have virtually anything in it; numbers, objects, strings anything, So when you set a[element] you are actually setting that particular property for the array.

a = 

a['see_this?'] = 'does this even make sense?'

You get the point.

What you ought to do is

let a = ;

data.forEach(element => {

  a.push(_getSupport(element))

});

// or

a = data.map(element =>_getSupport(element));

and then use your Promise.all; of course if this is piece of function code you need to return it so others can .then() on it, so return Promise.all()

This answer is almost identical to other answers, just two cents: you can use .map instead of forEach and push.

let getPromiseObj = data => new Promise((resolve, reject) =>

  setTimeout(

    () => resolve(data || ['No', 'truthy', 'data']),

    1000

  )

)



getPromiseObj()

  .then(res => Promise.all(res.map(getPromiseObj)))

  .then(finalRes => console.log(finalRes))

  .catch(e => console.error(e))

If you _getSupport is valid and does not throw an error to begin with you could also modify your code to something like this:

_getSupport()

  .then(data => {

    let a = ;

    data.forEach(element => a[element] = _getSupport(element))

    return Promise.all(a).then().catch(e => {})

  })

  .catch(e => console.log(e))

Where you also return the last Promise.all

Sometimes nested promises creates problems.

We need to accumulate promises into an array so that you can return them all.
That's why a.push() which will push the promises to the array.

The data in the next .then() function is an array of responses of each promise in the same order they are pushed.

Add console.log(data) to see on what values you are iterating on further.If data cannot be iterated then it might throw error.

Try to execute the "_getSupport()" function individually and see if you are getting any errors, if not then try my code it will work.

    _getSupport()

     .then((data) => {       

         let a = ;

         data.forEach(element => {

         a.push(_getSupport(element))

         });

         return Promise.all(a)

      })

     .then((data) => {

      // If it returns an array of elements then this data will be

      // [[0,1,2],[1,2,3] ...] based on the number of elements returned in 

      // first call

      })

     .catch( e => {console.log(e)})

Although all answers stimulated my brain, neither worked as expected.
The only solution I found stem from this answer :

 _getSupport() 

 .then((data) => {

                let sTypes = data.parameter.supported_types || ;

                sTypes.reduce((p,value,currentIndex) => {

                    return p.then(() => _getSupport({ method: "get_supported_scale", sType: value }));

                },Promise.resolve());                    

            })          

 .catch(e => {

        logger.error(e.stack);

  });