# Vaadin BrowserStorage Add-on Adds server-side logic and a JavaScript file to allow usage of local and session storage on the client's browser from server-side Vaadin code. This add-on should be forward-compatible up to Vaadin 23 and 24. Tested working with Vaadin 24. ## Usage The API for SessionStorage and LocalStorage are identical, and have been mapped to the Storage object API as returning completable futures, with the addition of a "contains key" function to potentially save on bandwidth, as follows: ```java CompletableFuture containsKey(String key); CompletableFuture getItem(String key); CompletableFuture setItem(String key, String value); CompletableFuture removeItem(String key); CompletableFuture clear(); ``` The returned boolean for `setItem`, `removeItem` and `clear` can safely be ignored for now; it is reserved for future use. To access `SessionStorage` or `LocalStorage`, create an instance of them: ```java LocalStorage localStorage = new LocalStorage(); localStorage.setItem("foo", "bar"); ``` Because the objects need to bind to a specific UI. In complex codebases, you may want to use the explicit constructor: ```java UI myUI = UI.getCurrent(); LocalStorage localStorage = new LocalStorage(myUI); localStorage.setItem("foo", "bar"); ``` The above examples are equivalent - the default constructor uses UI.getCurrent() internally to store a UI reference.