Documentation and minor correction

Author: loic-brtd

src/components/challenges/VideoSection.js

@@ -24,7 +24,7 @@ const VideoSection = ({ challenge }) => {
   const hasMultiParts = challenge.parts?.length > 0;
   const [showTimestamps, setShowTimestamps] = useState(!hasMultiParts);
 
-  const activePartIndex = useChallengePartIndex(challenge.parts?.length ?? 1);
+  const activePartIndex = useChallengePartIndex(challenge.parts?.length || 1);
   const activePart = challenge.parts?.[activePartIndex] ?? challenge;
   const { videoId, nebulaSlug, timestamps } = activePart;
   const hasTimestamps = timestamps?.length > 0;

src/components/tracks/VideoSection.js

@@ -35,7 +35,7 @@ const VideoSection = ({ track, video, trackPosition, mainTitle }) => {
 
   const { title, topics, languages } = video;
 
-  const totalParts = video.parts?.length ?? 1;
+  const totalParts = video.parts?.length || 1;
   const partIndex = useChallengePartIndex(totalParts);
   const part = video.parts?.[partIndex];
   const videoId = part?.videoId ?? video.videoId;

src/hooks/index.js

@@ -139,9 +139,13 @@ export const useIsFirstRender = () => {
 };
 
 /**
- * Returns the challenge part index (0 if the challenge is not multi-part)
- * which has been stored in the `location.state` object using the `Link.state`
- * property.
+ * If the current URL (and hash value) corresponds to a part from a multi-part
+ * coding challenge (within a challenge page or a track page), this hook returns
+ * the zero-based index of this part, else it returns 0.
+ *
+ * The hash value should look like `#part-3`. If the part number if larger than
+ * the `totalParts` parameter, the returned index corresponds to the last part
+ * of the challenge (`totalParts - 1`).
  *
  * @param totalParts {number} total number of parts of the challenge (1 if the
  * challenge is not multi-part)