sapper/test/app/routes/[x]/[y]/[z].html

<span>z: {segment} {count}</span>
<a href="foo/bar/qux"></a>

<script>
	import counts from '../_counts.js';

	export default {
		preload() {
			return {
				count: counts.z += 1
			};
		},

		oncreate() {
			this.set({
				segment: this.get().params.z
			});
		}
	};
</script>