Firebase Storage - Wait till all upload tasks are completed before executing function

Question

I\'m using the following code to upload one or multiple files to Firebase Storage. When the upload is completed the downloadURL is logged in the console.

I would lik

Answer 1

UploadTask objects behave just like promises, as they have then() and catch() methods. So, you can collect them all into an array and use Promise.all() to generate a another promise that resolves when all the uploads are complete.

const promises = [];
files.forEach(file => {
    const uploadTask = Storage.ref(`files/${file.name}`).put(file);
    promises.push(uploadTask);

    uploadTask.on('state_changed', snapshot => {
        const progress = (snapshot.bytesTransferred / snapshot.totalBytes) * 100;
        console.log(progress);
    }, error => { console.log(error) }, () => {
        uploadTask.snapshot.ref.getDownloadURL().then(downloadURL => {
            console.log(downloadURL);
        });
    });
});

Promise.all(promises).then(tasks => {
    console.log('all uploads complete');
});