Web Storage APIs Explained: localStorage, sessionStorage, and IndexedDB

Imagine This…

You’re building a to-do list app. Your user painstakingly enters their tasks for the day, hits refresh, and — poof! — all the tasks disappear. Frustrating, right? This is where Web Storage APIs come in to save the day. These tools let you store data in the browser so your app can remember the user’s tasks, preferences, and more — even if they close the tab or browser.

In this guide, we’ll explore localStorage, sessionStorage, and IndexedDB, breaking down when and how to use each. By the end, you’ll have the knowledge to build apps that feel smarter and more responsive.

Introduction: Your App’s Filing Cabinet

Think of your app’s data like a collection of notes in a filing cabinet. Some notes (like user preferences) need to stay forever, while others (like a shopping cart) should vanish when you close the app. Web Storage APIs are the tools that help you organize this “filing cabinet” with efficiency and clarity.

Overview of Web Storage APIs

Let’s break down the three main Web Storage APIs: localStorage, sessionStorage, and IndexedDB.

1. localStorage: The Persistent Filing Cabinet

• What it is: localStorage is a simple key-value storage mechanism that persists even after the browser is closed.