Add `isHidden` function

src/sidebar/util/annotation-metadata.js

@@ -149,6 +149,16 @@ export function isWaitingToAnchor(annotation) {
   );
 }
 
+/**
+ * Has this annotation hidden by moderators?
+ *
+ * @param {Object} annotation
+ * @return {boolean}
+ */
+export function isHidden(annotation) {
+  return !!annotation.hidden;
+}
+
 /**
  * Is this annotation a highlight?
  *

src/sidebar/util/test/annotation-metadata-test.js

@@ -234,6 +234,24 @@ describe('annotation-metadata', function() {
     });
   });
 
+  describe('.isHidden', () => {
+    it('returns `true` if annotation has been hidden', () => {
+      const annotation = fixtures.moderatedAnnotation({ hidden: true });
+      assert.isTrue(annotationMetadata.isHidden(annotation));
+    });
+
+    [
+      fixtures.newEmptyAnnotation(),
+      fixtures.newReply(),
+      fixtures.newHighlight(),
+      fixtures.oldAnnotation(),
+    ].forEach(nonHiddenAnnotation => {
+      it('returns `false` if annotation is not hidden', () => {
+        assert.isFalse(annotationMetadata.isHidden(nonHiddenAnnotation));
+      });
+    });
+  });
+
   describe('.isHighlight', () => {
     [
       {