ux: add scroll position lock for default docs sidebar

assets/js/app.js

@@ -0,0 +1,14 @@
+// Adds scroll position lock for default docs sidebar
+
+if (document.querySelector('#sidebar-default') !== null) {
+  let sidebar = document.getElementById('sidebar-default');
+
+  let pos = sessionStorage.getItem('sidebar-scroll');
+  if (pos !== null) {
+      sidebar.scrollTop = parseInt(pos, 10);
+  }
+
+  window.addEventListener('beforeunload', () => {
+      sessionStorage.setItem('sidebar-scroll', sidebar.scrollTop);
+  });
+}

layouts/docs/single.html

@@ -1,7 +1,7 @@
 {{ define "main" }}
 	<div class="row flex-xl-nowrap">
 		<div class="col-lg-5 col-xl-4 docs-sidebar d-none d-lg-block">
-			<nav class="docs-links" aria-label="Main navigation">
+			<nav {{ if eq .Site.Params.menu.section.collapsibleSidebar false }}id="sidebar-default" {{ end }}class="docs-links" aria-label="Main navigation">
 				{{ partial "sidebar/docs-menu.html" . }}
 			</nav>
 		</div>