First things first, create a new project on the Supabase platform. Make sure you grab those API keys and the database URL. You'll need them for API requests and integrations.

Next up, let's get the Supabase client library installed in your development environment. You can use either npm or yarn for this:

npm install @supabase/supabase-js

or

yarn add @supabase/supabase-js

Now, let's initialize the Supabase client with your project's URL and API key:

import { createClient } from '@supabase/supabase-js';

const supabaseUrl = 'https://your-project-ref.supabase.co';
const supabaseKey = 'your-anon-key';
const supabase = createClient(supabaseUrl, supabaseKey);

Head over to the Supabase dashboard, find the 'Storage' section, and create a new storage bucket. Give it a good name, as this bucket will hold your large file uploads. Set the permissions to public or private based on what you need.

To handle uploads from a client app, make sure Cross-Origin Resource Sharing (CORS) is set up correctly. Add your app's domain to the allowed origins in the Supabase settings.

For those big file uploads, a library like resumable.js can be super helpful. Install it using npm or yarn:

npm install resumablejs

Then, configure it in your app:

import Resumable from 'resumablejs';

const r = new Resumable({
    target: 'https://your-project-ref.supabase.co/storage/v1/object', // Base URL for Supabase storage API
    query: {
        bucket: 'your-bucket-name'
    },
    headers: {
        authorization: `Bearer ${supabaseKey}`
    },
    fileParameterName: 'file',
    chunkSize: 1 * 1024 * 1024, // 1MB chunks
});

Let's integrate the file input with resumable.js:

const fileInput = document.getElementById('file-input');
fileInput.addEventListener('change', (event) => {
    if (r.support) {
        r.addFiles(event.target.files); // Add the selected files
    }
});

// Handle file addition and upload
r.on('fileAdded', (file) => {
    r.upload(); // Start the upload upon file addition
});

r.on('fileSuccess', (file, message) => {
    console.log('File successfully uploaded:', message);
});

After the upload, check the Supabase dashboard under the Storage section to verify the uploaded file. Make sure the file chunks are correctly compiled into the final file.

For any post-upload processing, you can create a Supabase function or a serverless function triggered by the file upload. This can handle tasks like file validation, database updates, or sending notifications.

Keep an eye on the uploads using Supabase logs and console outputs in your app. Implement error handling in your client-side code to manage issues like network failures or incomplete uploads.

r.on('fileError', (file, error) => {
    console.error('Error uploading file:', error);
});

Following these steps will help you efficiently manage large file uploads in Supabase storage.