💾 localStorage & sessionStorage

Last Updated: 26th October 2025

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Both localStorage and sessionStorage are part of the Web Storage API, which allows you to store data in the browser.
They are used to save key–value pairs on the client side, without sending data to the server.

Hinglish Tip 🗣: Ye browser ke “mini databases” hain — data store hota hai bina server ke!

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🧩 Difference Between localStorage & sessionStorage

Feature	localStorage	sessionStorage
Data Lifetime	Stored permanently until manually cleared	Stored only for the current tab/session
Scope	Accessible across all browser tabs & windows	Accessible only within the same tab
Storage Limit	~5–10 MB	~5 MB
Example Use	Remember user theme, login token, preferences	Temporary data like form inputs or filters

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⚙️ Common Methods

Method	Description	Example
setItem(key, value)	Store a value	localStorage.setItem("name", "John")
getItem(key)	Retrieve a stored value	localStorage.getItem("name")
removeItem(key)	Remove a stored key	localStorage.removeItem("name")
clear()	Clear all stored data	localStorage.clear()
key(index)	Get key name by index	localStorage.key(0)

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🧠 localStorage Example

// Store data
localStorage.setItem("username", "BitDev");
localStorage.setItem("theme", "dark");

// Retrieve data
console.log(localStorage.getItem("username")); // BitDev

// Remove one item
localStorage.removeItem("theme");

// Clear all data
// localStorage.clear();

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🧠 sessionStorage Example

// Store temporary data
sessionStorage.setItem("sessionUser", "Guest");

// Retrieve data
console.log(sessionStorage.getItem("sessionUser")); // Guest

// Remove
sessionStorage.removeItem("sessionUser");

// Clear
sessionStorage.clear();

Hinglish Tip 🗣: Agar chahte ho data tab band hone ke baad bhi rahe, to localStorage use karo. Agar chahte ho data sirf ek session tak rahe, to sessionStorage use karo.

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🚫 Note

• Only string values can be stored.
• To store objects, use JSON.stringify() and JSON.parse():

const user = { name: "Amit", age: 22 };
localStorage.setItem("user", JSON.stringify(user));
console.log(JSON.parse(localStorage.getItem("user"))); // {name: "Amit", age: 22}

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💡 Quick Practice

• Store your name in localStorage and retrieve it.
• Store a temporary form input in sessionStorage.
• Try using clear() and check your browser’s Application → Storage tab.

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