Time to initialize the Supabase client in your app. Import it and set it up with your project's URL and API key.
```javascript
import { createClient } from '@supabase/supabase-js'

const supabaseUrl = 'https://xyzcompany.supabase.co'
const supabaseKey = 'public-anon-key'
const supabase = createClient(supabaseUrl, supabaseKey)
```

To insert multiple records into a table, you can do something like this:
```javascript
const users = [
{ name: 'John Doe', email: 'john@example.com' },
{ name: 'Jane Doe', email: 'jane@example.com' }
];

const { data, error } = await supabase
.from('users')
.insert(users);

if (error) console.error("Batch Insert Error:", error);
console.log("Inserted Data:", data);
```

Updating multiple records? Specify the criteria for selection and the new values like this:
```javascript
const updates = { email: 'new-email@example.com' };

const { data, error } = await supabase
.from('users')
.update(updates)
.in('id', [1, 2, 3]);

if (error) console.error("Batch Update Error:", error);
console.log("Updated Data:", data);
```

To delete multiple records at once, use the delete function with the right filter conditions.
```javascript
const { data, error } = await supabase
.from('users')
.delete()
.in('id', [4, 5, 6]);

if (error) console.error("Batch Delete Error:", error);
console.log("Deleted Data:", data);
```