bandolier-template/admin/bando/demos/Toastier.svelte.md

This demonstrates how to use the simple Toasts component, but it also shows how to use a function provided by a component in Svelte. The trick is to realize that functions are variables, and that Svelte will let you bind variables. You then simply have to do:

let send_toast;

In your script, and in your use of the component (Toasts) bind it like this:

<Toasts bind:send_toast />

Now when the Toasts component is loaded it will set your send_toast variable to the function so you can call it. In your component then you simple do:

export const send_toast = () => {
  // code here
}

Which will export it like a variable, but set it to const so Svelte doesn't complain that you aren't using it.