localStorage in Web Browser

localStorage is a small storage space inside your web browser. A website can use it to save information on your device, and the information stays there even after you close the browser or restart your computer.

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How it works

Think of it as a tiny notebook that each website gets to write in. Every entry has a name (called a key) and a value. A website can only read its own notebook, not the notebooks of other websites.

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Basic example

// Save something
localStorage.setItem('theme', 'dark');

// Read it back
const theme = localStorage.getItem('theme');

// Delete it
localStorage.removeItem('theme');

// Delete everything
localStorage.clear();

localStorage can only store text. To save an object or list, convert it first:

const user = { name: 'Ragul', age: 22 };

localStorage.setItem('user', JSON.stringify(user));

const saved = JSON.parse(localStorage.getItem('user'));

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What is it used for?

• Remembering dark mode or light mode
• Saving a draft of a form
• Keeping a to-do list
• Remembering a user's language choice

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Good things about it

• Easy to use
• Data stays after closing the browser
• Holds about 5 MB
• Works in all modern browsers

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Things to be careful about

• Not secure. Never store passwords or private tokens in it.
• Text only. Objects need JSON.stringify and JSON.parse.
• Small size. It is not meant for large data.
• Can be cleared. Users can delete it anytime from browser settings.