1 files changed, 48 insertions, 0 deletions
diff --git a/src/static/js/client/summary-nested-link.js b/src/static/js/client/summary-nested-link.js
new file mode 100644
index 00000000..23857fa5
--- /dev/null
+++ b/src/static/js/client/summary-nested-link.js
@@ -0,0 +1,48 @@
+/* eslint-env browser */
+
+import {
+  empty,
+  filterMultipleArrays,
+  stitchArrays,
+} from '../../shared-util/sugar.js';
+
+export const info = {
+  id: 'summaryNestedLinkInfo',
+
+  summaries: null,
+  links: null,
+};
+
+export function getPageReferences() {
+  info.summaries =
+    Array.from(document.getElementsByTagName('summary'));
+
+  info.links =
+    info.summaries
+      .map(summary =>
+        Array.from(summary.getElementsByTagName('a')));
+
+  filterMultipleArrays(
+    info.summaries,
+    info.links,
+    (_summary, links) => !empty(links));
+}
+
+export function addPageListeners() {
+  for (const {summary, links} of stitchArrays({
+    summary: info.summaries,
+    links: info.links,
+  })) {
+    for (const link of links) {
+      link.addEventListener('mouseover', () => {
+        link.classList.add('nested-hover');
+        summary.classList.add('has-nested-hover');
+      });
+
+      link.addEventListener('mouseout', () => {
+        link.classList.remove('nested-hover');
+        summary.classList.remove('has-nested-hover');
+      });
+    }
+  }
+}