HTML 5: Local Storage

Note: Session storage is also available (sessionStorage)

if (typeof(Storage) !== "undefined") {
    // Code for localStorage/sessionStorage.
} else {
    // Sorry! No Web Storage support..
}

Key value pairs, always strings at least 5Gb storage.

// Store
localStorage.setItem("lastname", "Smith");
// Retrieve
document.getElementById("result").innerHTML = localStorage.getItem("lastname");

Equivalent

// Store
localStorage.lastname = "Smith";
// Retrieve
document.getElementById("result").innerHTML = localStorage.lastname;

Delete via:

localStorage.removeItem("lastname");

Compatability