Event type typescript for event handler in Svelte

I'm using Typescript inside my svelte project, I need to define strong type for my event. But I can't find any way to do that.

<script lang="ts">  const onKeyUp = (event: [type here]) => {    console.log({ event })    // const {target, keyCode} = event  }</script><input type="text" on:keyup={onKeyUp} />

Anyone can help me!