sessionStorage

A web storage property that stores 5MB of key-value pairs per origin for the duration of a page session.

The sessionStorage API provides a synchronous mechanism for persisting string data within a single browser tab. Unlike localStorage, this data survives page reloads but is cleared immediately when the user closes the tab or window. Developers use the setItem() and getItem() methods to manage state (such as multi-step form inputs or temporary UI toggles) without taxing server resources. It operates on a per-origin basis and maintains a strict 5MB limit, making it the standard choice for sensitive, short-lived client-side data.

https://developer.mozilla.org/en-US/docs/Web/API/Window/sessionStorage