🚀 React Hooks & Rendering — A Clear Mental Model (For My Future Self Too)

🪝What are React Hooks?

Hooks are helpers that let a function component:

remember data

react to changes

🧠 Core React Hooks (WHAT + WHY)

🔹 useState — data that affects the UI

Why it exists:

React re-runs components often. Without state, values would reset every time.

Use when:

The user should see the change.

🔹 useEffect— side work after render

Why it exists:

Some work should happen after the UI is painted, not during it.

Used for:

API calls

timers

🔹useRef — remember without re-render

Why it exists:

Sometimes React needs to remember something without updating the UI.

Two main uses:

DOM access → focus input, scroll, measure

Silent storage → timer IDs, previous values, flags

🔹 useContext — shared/global data

Why it exists:

To avoid passing props through many layers.

Used for:

logged-in user

theme

🔹 useMemo — avoid heavy recalculations

Why it exists:

React re-runs components often → slow calculations can repeat unnecessarily.

Use when:

calculation is expensive

🔹 useCallback — stable functions

Why it exists:

Functions are recreated on every render.

Used mainly when:

passing callbacks to optimized child components

🌍 Rendering Types (WHY they exist)

🔹 CSR — Client Side Rendering

What: Browser builds the UI

Best for: dashboards, internal tools

🔹 SSR — Server Side Rendering

What: Server sends ready HTML

Why: Search engines need content

🔹 SSG — Static Site Generation

What: Page built once at build time

Why: Some content rarely changes

Hope it helps someone else too