Fundamental of Javascript

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- Fundamental of Javascript

• JavaScript in-depth Architecture

• let const var Difference

• TDZ ( temporal Dead Zone)

• function

  • Function Declaration or Function Statement ( it's hoisted)

  • Parameters vs Arguments

  • Function Expression ( not hoisted -> const getting = function getting(){console.log("Morning)})

  • pure function : It does not modify any external state or depend on external state that can change.

  • Anonymous Function

  • IIFE (Immediately Invoked Function Expression)

  • Arrow Function

  • curry Function

  • First-Class Function or Higher-Order Function

  • Callback Function

• lexical Environments

• block scope & scope chain

• Hoisting ( that is the process of memory Creation phase )

• Closer ( Bind Function and lexical environment )

• Errors

  • References Error

  • Type Error

• prototype, proto, proto chain

• shallow copy / deep copy

• Debounce && throttle concept

function debounce(func, delay) {
  let timer;
  return function (...args) {
    clearTimeout(timer);
    timer = setTimeout(() => {
      func(...args);
    }, delay);
  };
}

function throttle(func, delay) {
  let lastCall = 0;

  return function (...args) {
    const now = Date.now();
    if (now - lastCall >= delay) {
      lastCall = now;
      func(...args);
    }
  };
}

• Memorization

• class / call, bind, apply

• Promise API

  • Promise.all() -> promise all resolve or single rejected

  • Promise.allSettled() => rejected holeo baki gula resolved hobe

  • Promise.race() ->

  • Promise.any() -> j age resolved hobe return korbe aktao resolve na hole error

• async await

- Event Loop Concept

• synchronous vs asynchronous Concept

• Web Api

• micro task queue

• task queue / callback queue

• Starvation of task queue

- Fundamental of ReactJs

• Virtual DOM

• Reconciliation

• SSR

• CSR

• ISR

1. Server-Side Rendering (SSR)

In SSR, the server generates HTML for each request, and the browser receives a fully-rendered page.

Pros

1. SEO-Friendly: Fully-rendered HTML improves search engine indexing.

2. Fast First Contentful Paint (FCP): The user sees content faster because the server delivers ready-to-render HTML.

3. Dynamic Content: Ideal for pages where content changes frequently based on user interaction or server state.

Cons

1. Server Load: High traffic can overwhelm the server since HTML is generated for every request.

2. Slower TTFB (Time to First Byte): Generating HTML on the server adds processing time, delaying when the browser receives the first byte.

3. Complex Caching: It’s hard to cache SSR pages effectively because each request might generate unique content.

---

2. Client-Side Rendering (CSR)

In CSR, the browser receives a minimal HTML shell and JavaScript, which fetches and renders content dynamically.

Pros

1. Rich Interactivity: Ideal for highly interactive applications (e.g., SPAs) since updates happen without a full page reload.

2. Reduced Server Load: The server only serves static assets, reducing processing overhead.

3. Easier Scalability: Since rendering is offloaded to the client, scaling the server is simpler.

Cons

1. Poor Initial Load Time: Users see a blank page or loading spinner until JavaScript fetches and renders the content.

2. SEO Challenges: Search engines may struggle to index content that relies heavily on JavaScript.

3. Bundle Size Issues: Large JavaScript files can slow down page load times, especially on slower networks.

---

3. Incremental Static Regeneration (ISR)

ISR is a hybrid approach where static pages are generated at build time and updated incrementally after a specified revalidation period.

Pros

1. Performance: Combines the speed of static sites with the ability to serve up-to-date content.

2. SEO-Friendly: Generates fully-rendered static pages, ideal for search engines.

3. Dynamic Content: Supports dynamic content updates without rebuilding the entire site.

4. Reduced Server Load: Most users get cached static pages, reducing server overhead.

Cons

1. Stale Content: Pages can be out-of-date until they are regenerated during the revalidation period.

2. Implementation Complexity: Requires careful planning of revalidation intervals and content caching strategies.

3. Not Real-Time: Not suitable for content that needs to be updated instantaneously.

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When to Use Each?

• SSR: Use for dynamic applications with frequent updates, like news websites or e-commerce platforms with personalized content.

• CSR: Use for highly interactive applications, like dashboards or SPAs, where the client state is dynamic and constantly changing.

• ISR: Use for blogs, documentation sites, or e-commerce platforms where most content is relatively static but requires occasional updates.

Hybrid Approaches

Modern frameworks like Next.js allow you to mix SSR, CSR, and ISR in a single application, giving you the flexibility to optimize based on the specific requirements of different pages.

4o

You said:

How to implement in NExtJs

ChatGPT said:

ChatGPT

In Next.js, you can implement Server-Side Rendering (SSR), Client-Side Rendering (CSR), and Incremental Static Regeneration (ISR) for different pages depending on your application’s requirements. Here's how you can set up each:

---

1. Server-Side Rendering (SSR)

Next.js provides the getServerSideProps function for SSR. This function runs on the server for each request and returns the necessary data for rendering.

Example

jsxCopy code// pages/ssr-page.js
export async function getServerSideProps(context) {
  const res = await fetch('https://api.example.com/data');
  const data = await res.json();

  return { props: { data } }; // Props passed to the component
}

export default function SSRPage({ data }) {
  return (
    <div>
      <h1>Server-Side Rendering (SSR)</h1>
      <pre>{JSON.stringify(data, null, 2)}</pre>
    </div>
  );
}

---

2. Client-Side Rendering (CSR)

CSR is achieved by fetching data directly in a React component using hooks like useEffect.

Example

jsxCopy code// pages/csr-page.js
import { useEffect, useState } from 'react';

export default function CSRPage() {
  const [data, setData] = useState(null);

  useEffect(() => {
    fetch('https://api.example.com/data')
      .then((res) => res.json())
      .then((data) => setData(data));
  }, []);

  if (!data) return <p>Loading...</p>;

  return (
    <div>
      <h1>Client-Side Rendering (CSR)</h1>
      <pre>{JSON.stringify(data, null, 2)}</pre>
    </div>
  );
}

---

3. Incremental Static Regeneration (ISR)

Next.js supports ISR via the revalidate field in getStaticProps. This allows static pages to be rebuilt after a specified interval.

Example

jsxCopy code// pages/isr-page.js
export async function getStaticProps() {
  const res = await fetch('https://api.example.com/data');
  const data = await res.json();

  return {
    props: { data }, // Props passed to the component
    revalidate: 10, // Regenerate page every 10 seconds
  };
}

export default function ISRPage({ data }) {
  return (
    <div>
      <h1>Incremental Static Regeneration (ISR)</h1>
      <pre>{JSON.stringify(data, null, 2)}</pre>
    </div>
  );
}

---

4. Combining Approaches

You can combine SSR, CSR, and ISR within a single application. For example:

• Use SSR for dynamic content that changes frequently (e.g., user-specific dashboards).

• Use ISR for blog pages that need periodic updates.

• Use CSR for highly interactive pages like dashboards or settings pages.

Example: Combining in Next.js

jsxCopy code// pages/index.js
import Link from 'next/link';

export default function Home() {
  return (
    <div>
      <h1>Next.js Rendering Techniques</h1>
      <ul>
        <li><Link href="/ssr-page">SSR Example</Link></li>
        <li><Link href="/csr-page">CSR Example</Link></li>
        <li><Link href="/isr-page">ISR Example</Link></li>
      </ul>
    </div>
  );
}

---

5. Other Tips

• Dynamic Routes: You can use these methods for dynamic routes (e.g., pages/[id].js) with context.params in getStaticProps or getServerSideProps.

• Fallbacks in ISR: Use fallback: true or fallback: blocking in ISR to handle pages not generated at build time.

For example:

jsxCopy codeexport async function getStaticPaths() {
  const paths = [{ params: { id: '1' } }, { params: { id: '2' } }];
  return { paths, fallback: 'blocking' };
}

This flexibility makes Next.js an excellent choice for building applications with diverse rendering needs!

4o

- Fundamental of NodeJs