Does sessionStorage Expire

It doesn’t expire automatically. So if you never close your browser it never expires. So when the tab/window is closed the data is lost. Each sessionstorage area is allowed 5MB of storage (in some browsers 10MB).

Is it safe to use sessionStorage?

Both SessionStorage and LocalStorage are vulnerable to XSS attacks. Therefore avoid storing sensitive data in browser storage. It’s recommended to use the browser storage when there is, No sensitive data.

Where is sessionStorage stored?

The sessionStorage exists only within the current browser tab. Another tab with the same page will have a different storage. But it is shared between iframes in the same tab (assuming they come from the same origin).