First things first, head over to Supabase.io and sign up. Once you're in, create a new project. After that, you'll get your Supabase URL and anon public key. These are super important for initializing the Supabase client in your app.

Next, set up your database schema on Supabase. Think about the tables you'll need to represent the data for your real-time dashboard.

In your web app, you'll need to install the Supabase and Chart.js libraries. Just run these commands in your terminal:

npm install @supabase/supabase-js chart.js

And don't forget to include them in your app:

import { createClient } from '@supabase/supabase-js'
import Chart from 'chart.js/auto';

To get the Supabase client up and running, add this code to your app:

const supabase = createClient('Your-Supabase-Url', 'Your-anon-public-key')

Make sure to replace 'Your-Supabase-Url' and 'Your-anon-public-key' with your actual project details from Supabase.

Time to fetch some data from your Supabase tables. Here's an example of how to get data from a "sales" table:

const { data, error } = await supabase
  .from('sales')
  .select('*')

If your data is constantly changing and you want your dashboard to update in real-time, you can use Supabase's real-time subscriptions. Like this:

const subscription = supabase
.from('sales')
.on('*', payload => {
console.log('Change received!', payload)
})
.subscribe()

This will listen for changes in the 'sales' table and log them to the console.

Now, let's set up the charts for your data using Chart.js. It usually looks something like this:

const ctx = document.getElementById('myChart').getContext('2d');
const chart = new Chart(ctx, {
  type: 'bar',
  data: {
    labels: ['Sales'],
    datasets: [{
      label: '# of Sales',
      data: [], // Insert your data here
      backgroundColor: 'rgba(0, 123, 255, 0.5)',
    }]
  }
});

Finally, let's make sure your Chart.js data updates in real-time with the incoming data from your Supabase subscription:

const subscription = supabase
    .from('sales')
    .on('*', payload => {
        chart.data.datasets[0].data.push(payload.new.amount);
        chart.update(); 
    })
    .subscribe()

In this example, we're updating our chart every time a new record is added to the "sales" table. We're assuming the amount field of the incoming record represents the sale amount. Adjust this based on your actual data structure.

And there you have it! You've set up a real-time dashboard with Supabase and Chart.js!