Here we are going to HLS for Twitter like News Feed System.

1. Requirement

• It should loaded from top-bottom
• Infinity number of Stories I can scroll
• Support Image / Video per story
• User can add Comments under the Story

Non- Functional Requirement

• Should be responsive
• Optimization over all + image
• Offline Support

2. Mock Up UI

• As we need to achieve infinity scrolle
• we can use virtualization technique
• we will have 2 observers (Top and Bottom)
• and based on the intersection we will call API for the data.
• We need to maintain Position absolute and calculate height for arranging the stories
• We need to adjust the scroll position

NOTE:- We can also use alternate approach like
react-window and react-virtualized
https://www.npmjs.com/package/react-virtualized

3. Schema / State

Stories: {
id: {
id: string;
message: string;
articleLink: string;
imageLinks: Array<string>
}
}

comments: {
id: {
comment: string
likes: number;
likeType: string
}
}

4. API

1. getStories payload:
   • pageno
   • limit

getComments:
payload: [ids]

5. Real Time / Fetching Data

• Pooling (long / short)
  • while using pooling, we can use requestAnimationFrame to optimize when user is not in active tab.
  • We can use Exponential error fallback retry when error happen
• Http2/Push
• Socket.io/ web sockets
• server sent Events
• lets say user scroll and reach to the bottom Observer then we will call API to get the data.

6. Search For Story

• We need to use debounce/ thruttleing for optimized search calls.
• we can use filters to narrow down the search.
• we can use ; for searching multiple information

Optimization

7. Networking

• We can migrate to http/2, there we can send multiple requests in same time.
• then use can use bundle splitting (name.module.css)
• dynamic imports would have split into a bundle
• we can use defer the not immediately needed scripts
• we can use preload/prefetch attributes in CSS loading
• assets from CDN
• image lazy loading
• Compress image

8. Rendering

• Is always better to have a constant no of nodes
• No Height and width change dynamically, if we do so then the layout will shift then it is a CPU-intensive job.
• Animation use transform (GPU) calculation
• Checking lighting tools for web vitals and based on the result we can optimize further
• Flattern CSS selector, rather than deep nested CSS selectors better to give it a class name and then use it.
• Initial loading placeholder

9. Javascript

• For heavy / CPU intensive works we can add webworks to do the job
• we can use dynamic loading + lazy + suspense
• We can use Async Storage like index DB
• We will have service worker enabled with index DB we can achieve Offline support.
• We can add a Background sync mechanism.