For You → Campus Feed

Before you start

• Midterm roster is done — I will not edit that repo for this
• I copied the empty campus-feed starter (js/ is empty)
• I will type every .js file — no Fighter Arena paste

Full typed walkthrough: ACTIVITY-campus-feed.md

1. 1

   Create js/content.js.

2. 2

   Private #likes. Public like() and getLikes().

3. 3

   score() throws until a subclass writes it.

class Content {
  #likes = 0;
  constructor(creator, caption) {
    this.creator = creator;
    this.caption = caption;
  }
  like() { this.#likes += 1; }
  getLikes() { return this.#likes; }
  score() { throw new Error('implement score()'); }
}
globalThis.Content = Content;

If main.js can write post.likes = 999, encapsulation is missing.

1. 1

   Photo: score = likes.

2. 2

   Story: score = likes × 3, or 0 if hoursOld ≥ 24.

3. 3

   Reel: score = likes × 2 + watch seconds. Private #watchSeconds.

Photo  →  return this.getLikes()
Story  →  expired ? 0 : this.getLikes() * 3
Reel   →  return this.getLikes() * 2 + this.getWatchSeconds()

Same method name. Three formulas. That is the hook.

1. 1

   Feed HAS posts. It does not extend Content.

2. 2

   forYou() sorts by score() descending.

3. 3

   No instanceof. No if (kind === 'reel').

class Feed {
  #posts = [];
  add(post) { this.#posts.push(post); }
  forYou() {
    return this.#posts.slice().sort((a, b) => b.score() - a.score());
  }
}

If you add Poll later, Feed must stay untouched.

1. 1

   Seed one Photo, one expired Story, one fresh Story, one Reel.

2. 2

   Like them. Watch the reel. Use your campus captions.

3. 3

   Draw cards from forYou() into #feed.

4. 4

   Close the laptop and write Reel.score() on paper.

The dunk reel beats the 30-hour crush story. Do the math: 42 vs 0.

Done checklist

• New campus-feed repo — zero arena files
• Every js file typed by me
• #likes and #watchSeconds are private
• Feed.forYou() only calls score()
• Expired story scores 0
• I can write Reel.score() with the file closed