Window: sessionStorage property
===============================

 The read-only **`sessionStorage`**
 property accesses a session `Storage` object for the current
 origin. `sessionStorage` is similar to
 `localStorage`; the difference is that while data
 in `localStorage` doesn't expire, data in `sessionStorage` is
 cleared when the *page session* ends.

* Whenever a document is loaded in a particular tab in the browser, a unique page
 session gets created and assigned to that particular tab. That page session is valid
 only for that particular tab.
* A page session lasts as long as the tab or the browser is open, and survives over
 page reloads and restores.
* **Opening a page in a new tab or window creates a new session with the value
of the top-level browsing context, which differs from how session cookies
work.**
* Opening multiple tabs/windows with the same URL creates `sessionStorage`
 for each tab/window.
* Duplicating a tab copies the tab's `sessionStorage` into the new
 tab.
* Closing a tab/window ends the session and clears objects in
 `sessionStorage`.

 Data stored in `sessionStorage` **is specific to the protocol of the
page**. In particular, data stored by a script on a site accessed with HTTP
 (e.g., http://example.com) is
 put in a different `sessionStorage` object from the same site accessed with
 HTTPS (e.g., https://example.com).

 The keys and the values are *always* in the UTF-16 string
 format, which uses two bytes per character. As with objects, integer keys are
 automatically converted to strings.

Value
-----

 A `Storage` object which can be used to access the current origin's
 session storage space.

### Exceptions

`SecurityError`

Thrown in one of the following cases:

* The origin is not a valid scheme/host/port tuple. This can happen if the origin uses the `file:` or `data:` schemes, for example.
* The request violates a policy decision. For example, the user has configured the browsers to prevent the page from persisting data.

Note that if the user blocks cookies, browsers will probably interpret this as an instruction to prevent the page from persisting data.

Examples
--------

### Basic usage


```js
// Save data to sessionStorage
sessionStorage.setItem("key", "value");

// Get saved data from sessionStorage
let data = sessionStorage.getItem("key");

// Remove saved data from sessionStorage
sessionStorage.removeItem("key");

// Remove all saved data from sessionStorage
sessionStorage.clear();
```

### Saving text between refreshes

 The following example autosaves the contents of a text field, and if the browser is
 refreshed, restores the text field content so that no writing is lost.


```js
// Get the text field that we're going to track
let field = document.getElementById("field");

// See if we have an autosave value
// (this will only happen if the page is accidentally refreshed)
if (sessionStorage.getItem("autosave")) {
  // Restore the contents of the text field
  field.value = sessionStorage.getItem("autosave");
}

// Listen for changes in the text field
field.addEventListener("change", () => {
  // And save the results into the session storage object
  sessionStorage.setItem("autosave", field.value);
});
```


**Note:** Please refer to the Using the Web Storage API article for a full example.

Specifications
--------------

| Specification |
| --- |
| HTML Standard # dom-sessionstorage-dev |

Browser compatibility
---------------------

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

See also
--------

* Using the Web Storage API
* `Window.localStorage`