How to Create a Local Offline Database Using JavaScript and SQLite

Creating a local offline database using JavaScript and MySQL typically involves using a combination of technologies since JavaScript alone does not directly interact with MySQL databases. However, you can achieve this by using a local server setup with Node.js and a client-side database like SQLite. Here’s a general approach using Node.js and SQLite which is more suitable for local offline storage.

Step 1: Set Up Your Environment

Install Node.js: Make sure you have Node.js installed on your machine. You can download it from

Create a New Project: Run the following commands in your terminal to create a new directory and enter it.

mkdir local-database
 cd local-database
 npm init -y

Install SQLite3:

npm install sqlite3

Step 2: Create a Simple SQLite Database

Create a JavaScript file, e.g., database.js.

const sqlite3  require('sqlite3').verbose();// Create a new database or open an existing oneconst db  new ('./localDatabase.db');// Create a table(`CREATE TABLE IF NOT EXISTS users (  id INTEGER PRIMARY KEY AUTOINCREMENT,  name TEXT NOT NULL,  email TEXT NOT NULL UNIQUE)`);// Insert sample dataconst stmt  (`INSERT INTO users (name, email) VALUES (?, ?)`);('John Doe', 'john@');('Jane Doe', 'jane@');();// Query the database(`SELECT * FROM users`, function(err, rows) {  console.log(rows);});// Close the database connection();

Step 3: Run Your Script

In your terminal, run the script:

node database.js

Step 4: Accessing the Database in a Web Application

If you want to access this database from a web application running in the browser, you would typically use a server-side application like the one you’ve created to interact with the database and expose an API.

Set Up an Express Server

npm install express

Modify your database.js to have the following content:

const express  require('express');const sqlite3  require('sqlite3').verbose();const app  express();const db  new ('./localDatabase.db');(express.json());// API endpoint to get users('/users', (req, res) > {  ('SELECT * FROM users', function(err, rows) {    res.json(rows);  });});// Start the serverconst PORT  process.env.PORT || 3000;(PORT, () > {  console.log(`Server running on port ${PORT}`);});

Run the server

node database.js

Access the API

You can use tools like Postman or your browser to access http://localhost:3000/users to see the user data.

Conclusion

By following these steps, you can create a local SQLite database using JavaScript with Node.js, allowing you to store and retrieve data offline. For a fully offline experience, you would typically use IndexedDB in the browser, but that would not involve MySQL directly. If you specifically need MySQL, you would have to run a local MySQL server, which goes beyond a purely offline setup.