Svelte: how to pass `on:` event to a child component

Question

I want to create a component that will handle on:click, but without exporting an handleClick function; this is how it works right now

button.svelte:

<script lang="ts">
  export let handleClick: ((e: MouseEvent) => void ) | undefined = undefined
</script>
<button on:click={handleClick}>
  <slot></slot>
</button>

app.svelte:

<script lang="ts">
  import Button from '$lib/button/button.svelte'
</script>
<Button handleClick={() => console.log('click!')}>
  Click me!
</button>

How to change the Button element to use on:click directly in the app component?

app.svelte:

<Button on:click={handleClick}>
  <slot></slot>
</Button>

Answer 1

As per the Svelte documentation:

If the on: directive is used without a value, the component will forward the event, meaning that a consumer of the component can listen for it.

So you should be able to do this in button.svelte:

<button on:click>
  <slot></slot>
</button>

And then this should work in app.svelte:

<script>
import Button from './button.svelte';

const handleClick = (event) => {
  // …
};
</script>

<Button on:click={handleClick}>
  Foo
</Button>