How to fetch documents in a subcollection by their id in Firestore Database

I’m building a school managment system using HTML and Javascript in which, students must attend courses and I’m using this article as a guide: https://medium.com/firebase-tips-tricks/how-to-secure-many-to-many-relationships-in-firestore-d19f972fd4d3

I already have the Write part so I can associate courses with students, in the article this is
the code:

  const attendingRef = db.doc(`students/${studentId}/attending/${courseId}`);
  const attendeeRef = db.doc(`courses/${courseId}/attendees/${studentId}`);

  const batch = db.batch();
  batch.set(attendingRef, {});
  batch.set(attendeeRef, {});
  await batch.commit();
} 

But I had to make some changes to make it work in my project:

async function attendCourse() {
  
  
  const studentId = firebase.auth().currentUser.uid
  const courseId = "0O1OZOrtipgw8xlqNINc"
  const attendingRef = db.doc(`students/${studentId}/attending/${courseId}`);
  const attendeeRef = db.doc(`courses/${courseId}/attendees/${studentId}`);
  
  
  const batch = db.batch();
  batch.set(attendingRef, {});
  batch.set(attendeeRef, {});
  await batch.commit();
}

Now I want to fetch all the courses that a logged-in student attends and show them in a table, in the article it says that by using this I should be able to fetch the data:

async function fetchCourses(studentId) {
  const courseIds = await db.collection(`students/${studentId}/attending`).get();

  const courseDocs = await Promise.all(
    courseIds.docs.map(doc => db.doc(`courses/${doc.id}`).get())
  );

  return courseDocs.filter(doc => doc.exists).map(doc => ({ id: doc.id, ...doc.data() }));
} 

So I modified the code to make it work with my project aswell like this:

async function fetchCourses() {

  const studentId = firebase.auth().currentUser.uid
  const courseIds = await db.collection(`students/${studentId}/attending`).get();



  const courseDocs = await Promise.all(
    courseIds.docs.map(doc => db.doc(`courses/${doc.id}`).get())
  );
   
    console.log(courseDocs);

  return courseDocs.filter(doc => doc.exists).map(doc => ({ id: doc.id, ...doc.data() }));
  
}

Now, my console.log(courseDocs) shows a lot of things and amongst them is the id of the course that the student is attending but I want to show the title and content of that course in a table, any help is gladly appreciate.