Workbox makes it easy to create robust offline experiences in web applications. When a user navigates to a page without an internet connection, instead of showing an error, your application can serve a predefined fallback page, image or font.
page_fallback
can be a relative URL, a route name or a route name with parameters. See URL parameter for more information.
image_fallback
and font_fallback
refer to assets delivered by Asset Mapper or an URL to the font file.