JavaScript client installation in Supabase - Mini Project: Build & Apply

JavaScript Client Installation for Supabase

📖 Scenario: You are setting up a new web project that will use Supabase as its backend service. To start, you need to install and configure the Supabase JavaScript client so your web app can connect to the Supabase backend.

🎯 Goal: Install the Supabase JavaScript client and initialize it with the project URL and public API key.

📋 What You'll Learn

Install the Supabase JavaScript client using npm

Create a variable called supabaseUrl with the exact value "https://xyzcompany.supabase.co"

Create a variable called supabaseKey with the exact value "public-anonymous-key"

Initialize the Supabase client using createClient with supabaseUrl and supabaseKey

Create a variable called supabase to hold the client instance

💡 Why This Matters

🌍 Real World

This setup is the first step in building web applications that use Supabase as a backend service for authentication, database, and storage.

💼 Career

Knowing how to install and configure cloud service clients like Supabase is essential for frontend and full-stack developers working with modern cloud backends.

1

Install Supabase JavaScript Client

Write the exact npm command to install the Supabase JavaScript client package called @supabase/supabase-js.

Supabase

# Your code here

Hint

Use npm install followed by the package name.

2

Create Supabase URL and Key Variables

Create two variables: supabaseUrl set to "https://xyzcompany.supabase.co" and supabaseKey set to "public-anonymous-key".

Supabase

npm install @supabase/supabase-js

// Create supabaseUrl and supabaseKey variables below
# Your code here

Hint

Use const to declare variables with the exact string values.

3

Import and Initialize Supabase Client

Import createClient from @supabase/supabase-js and create a variable called supabase by calling createClient(supabaseUrl, supabaseKey).

Supabase

npm install @supabase/supabase-js

const supabaseUrl = "https://xyzcompany.supabase.co";
const supabaseKey = "public-anonymous-key";

// Import createClient and initialize supabase client below
# Your code here

Hint

Use ES module import syntax and call createClient with the two variables.

4

Complete Supabase Client Setup

Ensure the full code includes the npm install command, the two variables supabaseUrl and supabaseKey, the import statement for createClient, and the initialization of supabase client.

Supabase

npm install @supabase/supabase-js

const supabaseUrl = "https://xyzcompany.supabase.co";
const supabaseKey = "public-anonymous-key";

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

const supabase = createClient(supabaseUrl, supabaseKey);

// Finalize the setup if needed
# Your code here

Hint

Review all previous steps to ensure the full setup is present.

Practice

1. What is the correct command to install the Supabase JavaScript client using npm?

easy

A. npm install @supabase/supabase-js

B. npm install supabase-js

C. npm install supabase-client

D. npm install @supabase/client-js

Solution

1. Step 1: Identify the official package name

   The official Supabase JavaScript client package is named '@supabase/supabase-js'.

2. Step 2: Use npm install with the correct package

   The correct command is 'npm install @supabase/supabase-js' to install the client.

3. Final Answer:

   npm install @supabase/supabase-js -> Option A

4. Quick Check:

   Correct package name = npm install @supabase/supabase-js [OK]

Hint: Remember the package starts with '@supabase/' [OK]

Common Mistakes:

• Using incomplete package names
• Omitting the '@supabase/' prefix
• Confusing with other similar package names

2. Which of the following is the correct way to import the Supabase client in a JavaScript file after installation?

easy

A. const supabase = require('supabase-js');

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

C. import supabase from '@supabase/client';

D. const supabase = require('@supabase/supabase-js');

Solution

1. Step 1: Use ES module import syntax

   The Supabase client uses named export 'createClient' from '@supabase/supabase-js'.

2. Step 2: Confirm correct import statement

   The correct import is 'import { createClient } from '@supabase/supabase-js';'.

3. Final Answer:

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

4. Quick Check:

   Use named import 'createClient' from '@supabase/supabase-js' [OK]

Hint: Use named import with curly braces for createClient [OK]

Common Mistakes:

• Using default import instead of named import
• Using wrong package name in import
• Mixing require and import syntax

3. Given the following code snippet, what will be the output of console.log(supabaseUrl)?

import { createClient } from '@supabase/supabase-js';
const supabaseUrl = 'https://xyzcompany.supabase.co';
const supabaseKey = 'public-anonymous-key';
const supabase = createClient(supabaseUrl, supabaseKey);
console.log(supabaseUrl);

medium

A. https://xyzcompany.supabase.co

B. undefined

C. An error because supabaseUrl is not defined

D. 'public-anonymous-key'

Solution

1. Step 1: Identify the variable logged

   The code logs 'supabaseUrl', which is defined as a string URL.

2. Step 2: Confirm the value of supabaseUrl

   It is set to 'https://xyzcompany.supabase.co', so logging it prints this string.

3. Final Answer:

   https://xyzcompany.supabase.co -> Option A

4. Quick Check:

   Variable supabaseUrl = 'https://xyzcompany.supabase.co' [OK]

Hint: Check which variable is logged exactly [OK]

Common Mistakes:

• Confusing supabaseUrl with supabaseKey
• Assuming logging supabase object instead
• Thinking variable is undefined

4. What is wrong with this code snippet for creating a Supabase client?

import { createClient } from '@supabase/supabase-js';
const supabaseUrl = 'https://xyzcompany.supabase.co';
const supabaseKey = 'public-anonymous-key';
const supabase = createClient(supabaseKey, supabaseUrl);

medium

A. The supabaseUrl is missing the protocol

B. The import statement is incorrect

C. The supabaseKey should be an environment variable

D. The arguments to createClient are reversed; URL should be first

Solution

1. Step 1: Check the order of arguments in createClient

   The function expects the URL first, then the key.

2. Step 2: Identify the mistake in argument order

   The code passes the key first and URL second, which is incorrect.

3. Final Answer:

   The arguments to createClient are reversed; URL should be first -> Option D

4. Quick Check:

   createClient(url, key) order matters [OK]

Hint: Remember: URL first, key second in createClient() [OK]

Common Mistakes:

• Swapping URL and key arguments
• Ignoring import correctness
• Not using environment variables (though recommended)

5. You want to keep your Supabase key secure in a JavaScript project. Which is the best practice to handle the key?

hard

A. Publish the key in your public GitHub repository for easy access

B. Hardcode the key directly in your JavaScript files

C. Store the key in an environment variable and access it in your code

D. Send the key as a query parameter in URLs

Solution

1. Step 1: Understand security best practices for keys

   Keys should not be exposed in code or public places to avoid misuse.

2. Step 2: Use environment variables to keep keys secure

   Environment variables keep keys out of code and can be managed securely.

3. Final Answer:

   Store the key in an environment variable and access it in your code -> Option C

4. Quick Check:

   Use environment variables for secrets [OK]

Hint: Never hardcode keys; use environment variables [OK]

Common Mistakes:

• Hardcoding keys in source code
• Exposing keys publicly in repos
• Passing keys in URLs