Upload Files to Firebase Storage with JavaScript
Firebase; being a robust Realtime Database solution; it provides Storage of files as well. Learn how to upload files to Firebase Storage with JavaScript in simple steps

Firebase is has proved itself to be very robust Real-time Database solution; and with new API, it provides File Storage as well.
This reduces the Server-side headache of handling files to bare minimum.
We will be going through a simple application to upload images to the Firebase Hosting along with some basic CRUD operations and authentication with Firebase. As we have already covered both topics on following location, we will be concentrating more on the file upload.
If you are looking for how to upload files to PHP, you can read:
Upload files to PHP backend using fetch and FormData
Steps:
Basic process for file upload is
- create firebase storage reference
const ref = firebase.storage().ref();
- Now get the file to be uploaded from the
input[type="file"]
const file = $('#photo').get(0).files[0];
OR
const file = document.querySelector('#photo').files[0];
- Now prepare the filename and metadata for the uploaded file
- Filename we can easily get the name of file being uploaded by the name property of the file being uploaded as follows
const name = file.name;
but it is not a good idea to keep the file name as only identifier, we will use timestamp as well in the beginning of the file name as following
const name = (+new Date()) + '-' + file.name;
- Metadata Metadata needs the object which should contain
contentType
key.contentType
is the file type which can be taken from thefile.type
const metadata = { contentType: file.type };
- Create the file upload task, this file upload task will be handled by the
.put()
method on storage child. This task is a Promise and hence we can easily operate on this task laterconst task = ref.child(name).put(file, metadata);
The task also supports following methods to handle file upload:
// Pause the upload
task.pause();
// Resume the upload
task.resume();
// Cancel the upload
task.cancel();
- Use the response of file upload
task
.then(snapshot => snapshot.ref.getDownloadURL())
.then(url => console.log(url))
As in above steps, the file upload is complete, though there are few things to notice:
- You can save the
downloadURL
of the uploaded file like above; or you can save the fire ref and use it later to get the download URL like as follows
const image = ref.child('kingsman.jpg');
const urlPromise = image.getDownloadURL();
urlPromise.then(url => {
document.querySelector('#someImageTagID').src = url;
}
- There can be many cases of error which you will need to handle in the upload task by the
.catch()
method of promise like as follows:
task
.then(snapshot => snapshot.ref.getDownloadURL())
.then((url) => {
document.querySelector('#someImageTagID').src = url;
})
.catch((error) => {
// A full list of error codes is available at
// https://firebase.google.com/docs/storage/web/handle-errors
switch (error.code) {
case 'storage/unauthorized':
// User doesn't have permission to access the object
break;
case 'storage/canceled':
// User canceled the upload
break;
...
case 'storage/unknown':
// Unknown error occurred, inspect error.serverResponse
break;
}
});
- All properties of the returned
snapshot
are:
Property | Type | Writable |
---|---|---|
bucket | string | NO |
generation | string | NO |
metageneration | string | NO |
fullPath | string | NO |
name | string | NO |
size | number | NO |
timeCreated | string | NO |
updated | string | NO |
md5Hash | string | YES |
on upload | - | NO |
on updateMetadata | - | NO |
cacheControl | string | YES |
contentDisposition | string | YES |
contentEncoding | string | YES |
contentLanguage | string | YES |
contentType | string | YES |
downloadURLs | Array | NO |
customMetadata | Object | YES |
Final Code:
const ref = firebase.storage().ref();
const file = document.querySelector('#photo').files[0]
const name = (+new Date()) + '-' + file.name;
const metadata = {
contentType: file.type
};
const task = ref.child(name).put(file, metadata);
task
.then(snapshot => snapshot.ref.getDownloadURL())
.then((url) => {
console.log(url);
document.querySelector('#someImageTagID').src = url;
})
.catch(console.error);
Demo:
The movie DB demo which we created in earlier posts is now equipped with the moviePoster
upload as well.
Upload multiple files to Firebase in single Batch:
