Passing data between sibling components in Svelte

Question

How to pass data (ex: Navbar Title) to a component used in the parent element?

<!-- _layout.svelte -->
<script>
  import Nav from "../components/Nav.svelte";
  let navTitle = "MyApp";
</script>

<Nav {navTitle}/>
<slot />

<!-- Nav.svelte -->
<script>
  export let navTitle = "";
</script>
<h1>{navTitle}</h1>

<!-- Login.svelte -->
How to pass navTitle value from here to Nav.svelte?

To clarify, this needs to be scalable and to work on page load/transition for all routes of an SPA using Routify, preferably providing a default value and be able to have HTML value:

<!-- Article.svelte -->

<!-- User.svelte -->
navTitle is '<a href="/user">My Account </a>'

<!-- Comment.svelte -->

Answer 1

The easiest way to share data across components is to use stores as described in the docs

Your setup for that would be

<!-- Nav.svelte -->
<script>
  import { navTitle } from './store.js'
</script>
<h1>{$navTitle}</h1>

<!-- Login.svelte -->
<script>
  import { navTitle } from './store.js'

  navTitle.set('...')
</script>

<!-- store.js -->
import { writable } from 'svelte/store'

export const navTitle = writable('')