Facebook system (Keeping list/map inside each class)

gistfile1.txt

class User {
    constructor() {
        if (!User.users) {
            User.users = new Map();
        }
    }

    static registerUser(userId, userName) {
        if (!User.users.has(userId)) {
            const newUser = { userId, userName };
            User.users.set(userId, newUser);
            return newUser;
        }
        return "User already existed";
    }
}

class Post {
    constructor() {
        if (!Post.posts) {
            Post.posts = [];
        }
    }

    static addPost(userId, postContent) {
        Post.posts.push({ userId, posts: postContent });
        return "Added post successfully";
    }

    static getPosts() {
        return Post.posts;
    }
}

class Friend {
    constructor() {
        if (!Friend.friends) {
            Friend.friends = [];
        }
    }

    static addFriend(userId, friendId) {
        Friend.friends.push({ follower: userId, followee: friendId });
        Friend.friends.push({ follower: friendId, followee: userId });
        return "Added as friend";
    }

    static removeFriend(userId, friendId) {
        Friend.friends = Friend.friends.filter(friend => !(friend.followee === userId && friend.follower === friendId));
        Friend.friends = Friend.friends.filter(friend => !(friend.followee === friendId && friend.follower === userId));
        return "Unfriended successfully";
    }

    static getFriends() {
        return Friend.friends;
    }

    static getFriendPosts(userId) {
        const friendList = Friend.friends.filter(friend => friend.follower === userId).map(friend => friend.followee);
        return Post.getPosts().filter(post => friendList.includes(post.userId));
    }

    static searchFriendPosts(userId, search) {
        const friendList = Friend.friends.filter(friend => friend.follower === userId).map(friend => friend.followee);
        const postList = Post.getPosts().filter(post => friendList.includes(post.userId));
        return postList.filter(post => post.posts.toLowerCase().includes(search.toLowerCase()));
    }
}

// Usage example:
User.registerUser(1, 'Tanvir');
User.registerUser(2, 'Nadim');

Friend.addFriend(1, 2);

Post.addPost(1, 'Hello, friends!');
Post.addPost(2, 'Hi, Bangladesh!');

console.log("friendPost", Friend.getFriendPosts(1));
console.log("friendPost search", Friend.searchFriendPosts(1, "bangladesh"));
Friend.removeFriend(1, 2);