HTML5 Local Storage & Session Storage

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The Web Storage API provides two simple storage options in modern browsers:

 

Feature localStorage sessionStorage
Scope Across tabs, windows, browser sessions Only for the current tab and session
Expiry Never (unless manually cleared) Clears when the tab or window closes
Capacity ~5–10 MB ~5 MB
Use Case Persistent settings, themes, carts One-time forms, temp data in tab

Syntax

Set an item:

localStorage.setItem("key", "value");
sessionStorage.setItem("key", "value");

Get an item:

let val = localStorage.getItem("key");
let val2 = sessionStorage.getItem("key");

Remove an item:

localStorage.removeItem("key");
sessionStorage.removeItem("key");

Clear all:

localStorage.clear();
sessionStorage.clear();

Example

<input type="text" id="username" placeholder="Enter your name">
<button onclick="saveName()">Save</button>
<p id="greeting"></p>

<script>
  function saveName() {
    let name = document.getElementById("username").value;
    localStorage.setItem("username", name);
    showGreeting();
  }

  function showGreeting() {
    let savedName = localStorage.getItem("username");
    if (savedName) {
      document.getElementById("greeting").innerText = "Welcome, " + savedName + "!";
    }
  }

  // Load name on page load
  window.onload = showGreeting;
</script>
Run ›

When to Use

Use Case Use
Keep cart items until user returns localStorage
Temporary form draft sessionStorage
User preferences/theme localStorage
One-time OTP, login state sessionStorage
notepad
  • Do not store sensitive data (like passwords or tokens) in localStorage or sessionStorage.
  • Data is not encrypted and accessible via JavaScript (including browser extensions).
  • Safer alternatives for sensitive data: use cookies with HTTPOnly + Secure flags or server-side storage.
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