Supabase JS: The Ultimate Guide & Documentation

Hey guys! Let’s dive into the world of Supabase and its JavaScript library. If you’re looking to build a modern app with a fantastic backend, Supabase might just be your new best friend. This guide will walk you through everything you need to know about Supabase JS, from getting started to advanced usage. Let’s get started!

What is Supabase?

Supabase is an open-source Firebase alternative that provides all the backend features you need to build a scalable and secure application. Think of it as a complete backend-as-a-service (BaaS) platform. It gives you a PostgreSQL database, authentication, real-time subscriptions, edge functions, and storage, all wrapped up in an easy-to-use interface. It aims to make backend development straightforward , so you can focus on creating awesome user experiences. Supabase is designed to be highly scalable, meaning it can handle a large number of users and requests without slowing down. This is crucial for applications that expect rapid growth or experience traffic spikes. Supabase uses PostgreSQL, a robust and reliable open-source relational database. This gives you the flexibility and power of a traditional database with the convenience of a BaaS. You can write complex queries, define relationships between tables, and use advanced features like triggers and stored procedures. Security is a top priority for Supabase, with built-in features to protect your data and users. It supports secure authentication methods like email/password, social logins (Google, GitHub, etc.), and multi-factor authentication. It also provides tools for managing user permissions and access control, ensuring that only authorized users can access sensitive data. The real-time capabilities of Supabase allow you to build interactive and responsive applications. You can subscribe to database changes and receive updates in real time, enabling features like live chat, collaborative editing, and real-time dashboards. Supabase is not just a database; it’s a complete backend platform with a wide range of features. This includes storage for files and media, edge functions for serverless computing, and a powerful API for interacting with your backend. With Supabase, you can build everything from simple prototypes to complex production applications.

Why Use Supabase JS?

Supabase JS is the JavaScript client library that allows you to interact with your Supabase backend from your client-side application. It provides a simple and intuitive API for performing common tasks like querying data, authenticating users, and managing storage. Using Supabase JS can greatly simplify your frontend development workflow , allowing you to focus on building the user interface and user experience. Supabase JS provides a clean and straightforward API for interacting with your Supabase backend. This makes it easy to perform common tasks like querying data, inserting new records, updating existing records, and deleting data. With Supabase JS, you can quickly build features without getting bogged down in complex backend code. Supabase JS handles authentication seamlessly, providing methods for signing up users, signing in with email/password or social providers, managing user sessions, and implementing password recovery. This simplifies the process of adding authentication to your application and ensures that your users’ data is secure. Supabase JS also provides methods for interacting with Supabase Storage, allowing you to upload, download, and manage files and media directly from your client-side application. This makes it easy to build features like image galleries, file sharing, and document management. Supabase JS supports real-time subscriptions, allowing you to subscribe to database changes and receive updates in real time. This enables you to build interactive and responsive applications with features like live chat, collaborative editing, and real-time dashboards. Supabase JS is designed to be lightweight and performant, ensuring that it doesn’t add unnecessary overhead to your client-side application. It’s also actively maintained and regularly updated with new features and improvements, so you can be confident that you’re using a reliable and up-to-date library. Using Supabase JS can significantly speed up your development process and reduce the amount of code you need to write. It provides a convenient and efficient way to interact with your Supabase backend, allowing you to focus on building the features that matter most to your users.

Getting Started with Supabase JS

Alright, let’s get our hands dirty and start using Supabase JS ! First, you’ll need to set up a Supabase project. Head over to supabase.com and create a new project. Once you’ve got your project set up, grab your Supabase URL and anon key from the project settings. These are essential for connecting your application to your Supabase backend. You can install Supabase JS using npm or yarn:

npm install @supabase/supabase-js

or

yarn add @supabase/supabase-js

Now, let’s initialize the Supabase client in your JavaScript file:

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

const supabaseUrl = 'YOUR_SUPABASE_URL'
const supabaseAnonKey = 'YOUR_SUPABASE_ANON_KEY'

const supabase = createClient(supabaseUrl, supabaseAnonKey)

Replace YOUR_SUPABASE_URL and YOUR_SUPABASE_ANON_KEY with the actual values from your Supabase project. With the Supabase client initialized, you’re now ready to start interacting with your database, authenticate users, and manage storage. Initializing the Supabase client is a crucial step in setting up your application to use Supabase. The createClient function takes two arguments: the Supabase URL and the Supabase anon key. These values are unique to your Supabase project and are used to authenticate your application with the Supabase backend. Make sure to keep these values secure and avoid exposing them in your client-side code. Once you have initialized the Supabase client, you can use it to perform various operations, such as querying data, inserting new records, updating existing records, and deleting data. You can also use it to authenticate users, manage user sessions, and implement password recovery. The Supabase client provides a simple and intuitive API for interacting with your Supabase backend, making it easy to build features without getting bogged down in complex backend code.

Basic Operations with Supabase JS

Now that we’ve set everything up, let’s look at some basic operations you can perform with Supabase JS . We’ll cover querying data, inserting data, updating data, and deleting data. These are the fundamental building blocks for interacting with your database.

Querying Data

To query data from your Supabase database, you can use the from() method to specify the table you want to query and the select() method to specify the columns you want to retrieve. Here’s an example:

async function fetchData() {
  const { data, error } = await supabase
    .from('your_table')
    .select('*')

  if (error) {
    console.error('Error fetching data:', error)
  } else {
    console.log('Data:', data)
  }
}

fetchData()

Replace your_table with the name of your table. The select('*') part tells Supabase to retrieve all columns from the table. If you only want to retrieve specific columns, you can specify them like this: select('column1, column2') . The from() method is used to specify the table you want to query. This is the starting point for building your query. You can chain other methods to the from() method to further refine your query, such as select() , where() , order() , and limit() . The select() method is used to specify the columns you want to retrieve from the table. You can use the wildcard character * to retrieve all columns, or you can specify a comma-separated list of column names. The where() method is used to add a filter to your query, allowing you to retrieve only the rows that match certain criteria. The order() method is used to sort the results of your query, and the limit() method is used to limit the number of rows returned.

Inserting Data

To insert data into your Supabase database, you can use the from() method to specify the table you want to insert data into and the insert() method to specify the data you want to insert. Here’s an example:

async function insertData() {
  const { data, error } = await supabase
    .from('your_table')
    .insert([
      {
        column1: 'value1',
        column2: 'value2',
      },
    ])

  if (error) {
    console.error('Error inserting data:', error)
  } else {
    console.log('Data inserted:', data)
  }
}

insertData()

Replace your_table with the name of your table, and column1 and column2 with the names of the columns you want to insert data into. The insert() method takes an array of objects, where each object represents a row of data to be inserted. The from() method is used to specify the table you want to insert data into. The insert() method is used to insert one or more rows of data into the table. You can insert a single row of data by passing an object to the insert() method, or you can insert multiple rows of data by passing an array of objects. Each object represents a row of data to be inserted and should contain the column names and values for each column. The insert() method returns a promise that resolves to an object containing the inserted data and any errors that occurred. If the insertion was successful, the data property will contain an array of objects representing the inserted rows. If an error occurred, the error property will contain an error object with more information about the error.

Updating Data

To update data in your Supabase database, you can use the from() method to specify the table you want to update data in, the update() method to specify the data you want to update, and the eq() method to specify the row you want to update. Here’s an example:

async function updateData() {
  const { data, error } = await supabase
    .from('your_table')
    .update({
      column1: 'new_value1',
      column2: 'new_value2',
    })
    .eq('id', 1)

  if (error) {
    console.error('Error updating data:', error)
  } else {
    console.log('Data updated:', data)
  }
}

updateData()

Replace your_table with the name of your table, column1 and column2 with the names of the columns you want to update, and id with the name of the column you want to use to identify the row to update. The eq() method is used to specify that you only want to update the row where the id column is equal to 1 . The from() method is used to specify the table you want to update data in. The update() method is used to update one or more rows of data in the table. The eq() method is used to add a filter to your query, allowing you to update only the rows that match certain criteria. In this example, we are using the eq() method to update the row where the id column is equal to 1 . You can use other methods like neq() , gt() , gte() , lt() , and lte() to add different types of filters to your query.

Deleting Data

To delete data from your Supabase database, you can use the from() method to specify the table you want to delete data from and the delete() method to specify the row you want to delete. Here’s an example:

async function deleteData() {
  const { data, error } = await supabase
    .from('your_table')
    .delete()
    .eq('id', 1)

  if (error) {
    console.error('Error deleting data:', error)
  } else {
    console.log('Data deleted:', data)
  }
}

deleteData()

Replace your_table with the name of your table and id with the name of the column you want to use to identify the row to delete. The eq() method is used to specify that you only want to delete the row where the id column is equal to 1 . The from() method is used to specify the table you want to delete data from. The delete() method is used to delete one or more rows of data from the table. The eq() method is used to add a filter to your query, allowing you to delete only the rows that match certain criteria. In this example, we are using the eq() method to delete the row where the id column is equal to 1 . You can use other methods like neq() , gt() , gte() , lt() , and lte() to add different types of filters to your query. The delete() method returns a promise that resolves to an object containing the deleted data and any errors that occurred. If the deletion was successful, the data property will contain an array of objects representing the deleted rows. If an error occurred, the error property will contain an error object with more information about the error.

Authentication with Supabase JS

Authentication is a crucial part of most applications. Supabase makes it easy to handle user authentication with its built-in authentication features and Supabase JS. Let’s see how to sign up, sign in, and sign out users.

Signing Up Users

To sign up users with email and password, you can use the signUp() method. Here’s an example:

async function signUpUser() {
  const { data, error } = await supabase.auth.signUp({
    email: 'user@example.com',
    password: 'your_password',
  })

  if (error) {
    console.error('Error signing up:', error)
  } else {
    console.log('User signed up:', data)
  }
}

signUpUser()

Replace user@example.com with the user’s email address and your_password with their desired password. The signUp() method takes an object with the email and password properties. You can also include other properties like options to customize the signup process. The signUp() method returns a promise that resolves to an object containing the user data and any errors that occurred. If the signup was successful, the data property will contain an object with the user’s information. If an error occurred, the error property will contain an error object with more information about the error. You can use the error object to display an error message to the user.

Signing In Users

To sign in users with email and password, you can use the signInWithPassword() method. Here’s an example:

async function signInUser() {
  const { data, error } = await supabase.auth.signInWithPassword({
    email: 'user@example.com',
    password: 'your_password',
  })

  if (error) {
    console.error('Error signing in:', error)
  } else {
    console.log('User signed in:', data)
  }
}

signInUser()

Replace user@example.com with the user’s email address and your_password with their password. The signInWithPassword() method takes an object with the email and password properties. The signInWithPassword() method returns a promise that resolves to an object containing the user data and any errors that occurred. If the sign-in was successful, the data property will contain an object with the user’s information. If an error occurred, the error property will contain an error object with more information about the error. You can use the error object to display an error message to the user.

Signing Out Users

To sign out users, you can use the signOut() method. Here’s an example:

async function signOutUser() {
  const { error } = await supabase.auth.signOut()

  if (error) {
    console.error('Error signing out:', error)
  } else {
    console.log('User signed out')
  }
}

signOutUser()

The signOut() method signs out the current user and removes their session from local storage. The signOut() method returns a promise that resolves to an object containing any errors that occurred. If the sign-out was successful, the error property will be null . If an error occurred, the error property will contain an error object with more information about the error. You can use the error object to display an error message to the user.

Realtime Subscriptions with Supabase JS

Realtime subscriptions are a powerful feature that allows you to listen for changes in your Supabase database in real time. This is great for building collaborative applications, live dashboards, and more. Supabase JS makes it easy to set up realtime subscriptions.

supabase
  .channel('any')
  .on(
    'postgres_changes',
    { event: '*', schema: 'public', table: 'your_table' },
    (payload) => {
      console.log('Change received!', payload)
    }
  )
  .subscribe()

Replace your_table with the name of the table you want to subscribe to. This code sets up a realtime subscription that listens for all changes (inserts, updates, deletes) on the specified table. When a change occurs, the callback function is called with the payload containing the details of the change. The channel() method is used to create a channel for the realtime subscription. You can use any string as the channel name. The on() method is used to listen for changes on the channel. The first argument is the event type, which is postgres_changes for database changes. The second argument is an object that specifies the filters for the changes you want to listen to. The event property specifies the type of event you want to listen to, which can be INSERT , UPDATE , DELETE , or * for all events. The schema property specifies the database schema you want to listen to, which is typically public . The table property specifies the table you want to listen to. The third argument is a callback function that will be called when a change occurs. The callback function receives a payload object with information about the change, such as the type of event, the table that was changed, and the new and old values of the changed row.

Conclusion

So there you have it – a comprehensive guide to Supabase JS ! We’ve covered everything from setting up your project to performing basic database operations, handling authentication, and setting up realtime subscriptions. With this knowledge, you’re well-equipped to build amazing applications with Supabase. Keep experimenting, keep learning, and have fun building awesome stuff! Remember, Supabase is constantly evolving, so stay tuned for new features and updates. Happy coding, guys!