A custom component that adds a favicon and a badge that you can use to show for example number of unread messages, etc.
Install via npm i svelte-favicon-badge
and simply import the component and add it to your markup. It's probably a good idea to only use one per page/route since there could be conflicts.
The options are: count
background
color
and href
<script>
import Badge from "svelte-favicon-badge";
let count = 0;
let background = "#FF0000";
let color = "#FFFFFF";
</script>
<Badge {count} {color} {background} href="favicon.png" />
Should support all modern browsers except Safari. Not tested in IE but is assumed not to work.