Why React Hydration Exists

When a server sends HTML to your browser, the page already looks complete before any JavaScript finishes loading.

But looks can be misleading. Buttons don't respond. Forms don't submit. Dropdowns don't open.

Hydration is the process where React attaches JavaScript to that existing HTML, making it interactive instead of rebuilding the page from scratch.

This is also why JavaScript bundle size matters so much. The browser can't hydrate components until it has downloaded, parsed, and executed their JavaScript.

That's why modern frameworks push more work to the server. Not because JavaScript is bad, but because sending less of it usually means users can interact with the page sooner.

📌 React Isn't the Problem

A React app doesn't become slow overnight. It becomes slow when unnecessary render accumulates overtime.

A render is React running a component again to determine what should appear on the screen.

Most developers reach for useMemo, useCallback, or another optimization as soon as performance drops. That's often treating the symptom.

The better question is:
Why did this component render in the first place?

Open React DevTools and enable Highlight updates. Click around your app.

If your navigation bar flashes every time you type into a search box, you've already found a performance issue.

Your useEffect Might be Doing Too Much

An effect is code that runs after React updates the screen, usually for interacting with things outside React.

Examples: Fetching data, Subscribing to events, Updating the document title.

The problem starts when developers use it for normal calculations.

Example:

useEffect(() => {
  setTotal(price * quantity)
}, [price, quantity])

This creates unnecessary work. total can already be calculated during rendering.

The effect adds another state update, another render, and another thing to debug.

A useful question:

Does this code synchronize with something outside React?

If not, it probably doesn't belong inside useEffect.

📘 You Don't Know JS Yet: Async & Performance

✍️ Author: Kyle Simpson

🗓 Year: 2015

📄 Pages: 296

🧠 No matter how much experience you have with JavaScript, odds are you don't fully understand the language. As part of the "You Don't Know JS" series, this concise yet in-depth guide focuses on new asynchronous features and performance techniques - including Promises, generators, and Web Workers - that let you create sophisticated single-page web applications and escape callback hell in the process.

#JavaScript

Git Rebase Explained

A rebase takes your commits and moves them on top of another branch, creating a cleaner history.

Imagine:

main:
A---B---C

feature:
     D---E

After rebasing:

main:
A---B---C---D---E

Your feature looks like it was created from the latest version of main.

Teams use it:
- To maintain cleaner commit history.
- For easier code reviews.
- Fewer unnecessary merge commits.

📌 The rule: Rebase your local work. You have to be careful rebasing commits that other people already use.

🔥 7 Free AI Tools for Developers You Should Try

If you're learning to code or building projects, these AI tools can save you hours every week 👨‍💻⚡️

1. Cursor 💻
• AI-powered code editor
• Write, debug and understand code faster

2. GitHub Copilot 🤖
• AI coding assistant
• Get code suggestions directly in your editor

3. Replit 🚀
• Code and build projects in your browser
• AI assistance + instant deployment

4. v0 🎨
• Generate UI from text prompts
• Great for quickly creating web interfaces

5. Bolt.new ⚡️
• Build full-stack applications using prompts
• Useful for quickly prototyping ideas

6. Lovable 🛠
• Create web apps using natural language
• Great for turning ideas into working prototypes

7. Phind 🔎
• AI search built for developers
• Useful for technical questions and debugging

💾 Save this list for your next project.