await response of image upload before continue function

Question

So I am working on a upload function for multiple images in an array. After a lot of struggling I have finally got my upload function to work and the images are showing up i

Answer 1

Most of your uploadImages() code was correct, however in many places you didn't return the promise from each asynchronous action.

Quick sidestep: Handling many promises

When working with lots of asynchronous tasks based on an array, it is advised to map() the array to an array of Promises rather than use a for loop. This allows you to build an array of promises that can be fed to Promise.all() without the need to initialise and push to another array.

let arrayOfPromises = someArray.map((entry) => {
    // do something with 'entry'
    return somePromiseRelatedToEntry();
  });

Promise.all(arrayOfPromises)
  .then((resultsOfPromises) => {
    console.log('All promises resolved successfully');
  })
  .catch((err) => {
    // an error in one of the promises occurred
    console.error(err);
  })

The above snippet will fail if any of the contained promises fail. To silently ignore individual errors or defer them to handle later, you just add a catch() inside the mapped array step.

let arrayOfPromises = someArray.map((entry) => {
    // do something with 'entry'
    return somePromiseRelatedToEntry()
      .catch(err => ({hasError: true, error: err})); // silently ignore errors for processing later
  });

Updated uploadImages() code

Updating your code with these changes, gives the following result:

uploadImages = () => {
    const provider = firebase.database().ref(`providers/${uid}`);
    // CHANGED: removed 'let imagesArray = [];', no longer needed

    return Promise.all(photos) // CHANGED: return the promise chain
        .then(photoarray => {
            console.log('all responses are resolved successfully');
            // take each photo, upload it and then return it's download URL
            return Promise.all(photoarray.map((photo) => { // CHANGED: used Promise.all(someArray.map(...)) idiom
              let file = photo.data;
              const path = "Img_" + uuid.v4();
              const storageRef = firebase // CHANGED: renamed 'ref' to 'storageRef'
                    .storage()
                    .ref(`/${uid}/${path}`);
              let metadata = {
                  contentType: 'image/jpeg',
              };

              // upload current photo and get it's download URL
              return storageRef.putString(file, 'base64', metadata) // CHANGED: return the promise chain
                .then(() => {
                  console.log(`${path} was uploaded successfully.`);
                  return storageRef.getDownloadURL() // CHANGED: return the promise chain
                    .then(fileUrl => ({uri: fileUrl}));
                });
            }));
        })
        .then((imagesArray) => {                       // These lines can
          console.log("Out-imgArray: ", imagesArray)   // safely be removed.
          return imagesArray;                          // They are just
        })                                             // for logging.
        .catch((err) => {
          console.error(err);
        });
};