Send temporary Data after a Redirect
"This is a Sveltekit library that passes temporary data to the next request, usually from form actions and endpoints. It's useful when you want a success or failure message displayed after a POST, which should not always be displayed at the form, but rather as a message on the page that the request was redirected to.
Since it's a temporary message, it's also known as a "flash message", known from PHP apps since it's easy to add this functionality with PHP's built-in session handling. With SvelteKit it's a bit harder, but this library was made to alleviate that, encouraging well-behaved web apps that redirect after a POST."