Managing session storage across different tabs or windows in JavaScript

21 Sep 2023

sessionstorage

Session storage in JavaScript provides a way to store data on the client side that persists until the browser window or tab is closed. However, by default, session storage is isolated to a single tab or window. This means that if you have multiple tabs or windows open for the same website, each one will have its own independent session storage.

In some cases, you may want to share session data across different tabs or windows of the same website. In this blog post, we will explore how to achieve this using a technique called “Broadcast Channel”.

Broadcast Channel

Broadcast Channel is an API introduced in HTML5 that allows communication between different browsing contexts, such as tabs or windows, that are opened for the same website.

To use Broadcast Channel for sharing session storage, follow these steps:

Create a new Broadcast Channel instance in each tab or window where you want to share the session storage data.
```
const channel = new BroadcastChannel('sessionStorageChannel');
```
The argument 'sessionStorageChannel' is a unique identifier for the channel. Make sure to use the same identifier in all tabs or windows.
Listen for messages on the broadcast channel and update the session storage accordingly.
```
channel.addEventListener('message', event => {
  const { key, value } = event.data;
  sessionStorage.setItem(key, value);
});
```
Whenever a message is received on the channel, this event listener will extract the key-value pair from the data and update the session storage accordingly.
Broadcast session storage changes to other tabs or windows.
```
function updateSessionStorage(key, value) {
  sessionStorage.setItem(key, value);
  channel.postMessage({ key, value });
}
```
This function updates the session storage in the current tab or window and then broadcasts the changes to other tabs or windows by posting a message on the broadcast channel.

By utilizing the Broadcast Channel API, you can now achieve synchronized session storage across multiple tabs or windows of the same website. This can be particularly useful in scenarios where you need to maintain a shared state or synchronize data between different instances of your web application.

#javascript #sessionstorage