Improved accessibility of sidebar navigation

src/assets/javascripts/bundle.ts

@@ -43,6 +43,8 @@ import {
 import { configuration, feature } from "./_"
 import {
   at,
+  getActiveElement,
+  getElement,
   getOptionalElement,
   requestJSON,
   setLocation,
@@ -186,6 +188,18 @@ keyboard$
           if (typeof next !== "undefined")
             setLocation(next)
           break
+
+        /* Expand navigation, see https://bit.ly/3ZjG5io */
+        case "Enter":
+          const active = getActiveElement()
+          if (active instanceof HTMLLabelElement) {
+            const id = `[id="${active.htmlFor}"]`
+            const input = getElement<HTMLInputElement>(id)
+            active.setAttribute(
+              "aria-expanded",
+              `${input.checked = !input.checked}`
+            )
+          }
       }
     })