When you upload a file, you can also store some metadata for that file, such as Content-Type or name.

You can create a JSON object with key: value pairs and pass that object when you upload the file. For custom metadata, you can create an object inside the metadata object, as shown here:

// Create file metadata including the content type
var metadata = {
  contentType: 'image/jpeg',
  customMetadata: {
      'ticketNo':'12345'
  }
};

// Upload the file and metadata
var uploadTask = storageRef.child('folder/file.jpg').put(file, metadata);