make sure highlighted item in search result is scrolled into view when using keyboard to navigate

Author: mojavelinux

src/js/vendor/docsearch.bundle.js

@@ -23,6 +23,7 @@
     var autocomplete = eventEmitter.autocomplete
     autocomplete.setVal()
     eventEmitter.on('autocomplete:selected', disableClose)
+    controller.input.data('aaAutocomplete').dropdown._ensureVisible = ensureVisible
     searchForm.addEventListener('click', confineEvent)
     document.documentElement.addEventListener('click', resetSearch.bind(autocomplete))
     if (controller.input.attr('autofocus') != null) controller.input.focus()
@@ -42,6 +43,22 @@
     }
   }
 
+  function ensureVisible (el) {
+    var item = el.get(0)
+    var container = item
+    while ((container = container.parentNode) && container !== document.documentElement) {
+      if (window.getComputedStyle(container).overflowY === 'auto') break
+    }
+    if (!container || container.scrollHeight === container.offsetHeight) return
+    var delta
+    if ((delta = 15 + item.offsetTop + item.offsetHeight - (container.offsetHeight + container.scrollTop)) > 0) {
+      container.scrollTop += delta
+    }
+    if ((delta = item.offsetTop - container.scrollTop) < 0) {
+      container.scrollTop += delta
+    }
+  }
+
   function resetSearch () {
     this.close()
     this.setVal()