What is the significance of the React Fiber architecture?
This question is asked a lot in Interviews. Let us try to answer it briefly.
Before Fiber, React was like a chef who started an order and refused to stop until it was finished, even if a more important customer walked in. With Fiber, the chef learned how to multitask, pause, and prioritize.
1. Breaking the "All-or-Nothing" Rule
In the old version of React (the "Stack" reconciler), once the engine started updating your screen, it couldn't be stopped. If you had a massive list of items to render, the browser might "freeze" for a split second because React was hogging all the processing power.
Fiber changed this by breaking work into tiny chunks. Instead of doing everything in one giant burst, React now does a little bit of work, checks if the browser needs to do something else (like handle a mouse click or play an animation), and then comes back to finish the job.
2. Priority Scheduling
Not all updates on a website are equally important. Fiber allows React to rank tasks:
- High Priority: A user typing into a search bar or clicking a button. These need to feel instant.
- Low Priority: Loading data at the bottom of the page or updating a footer. These can wait a few milliseconds.
3. Better Performance (The "Jank" Factor)
You know when a website feels "laggy" while you scroll? That’s called jank. It happens when the browser can't keep up with the frame rate (usually 60 frames per second).
Because Fiber can pause its work to let the browser draw the next frame, it keeps the experience smooth, even when complex things are happening behind the scenes.
Quick Cheatsheet
| Feature | Old React (Stack) | New React (Fiber) |
|---|---|---|
| Work Style | One big, unstoppable block. | Small, pause-able chunks. |
| Urgency | First come, first served. | Important tasks jump to the front. |
| User Feel | Can feel "frozen" during heavy loads. | Stays responsive and fluid. |
In short, Fiber is the foundation that allows modern React features (like Hooks and Suspense) to exist. It turned React from a fast engine into a smart engine.
