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very common problem with large forms:

❌ When you submit a big form and Laravel validation fails, it refreshes the page and shows errors… 😩 But the user has to fill everything again or scroll a lot, which is frustrating.

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✅ SOLUTION (Best Practice): Use old() values + show validation errors properly

You do NOT need to re-enter the entire form if you use Laravel’s built-in helpers the right way.

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🔹 Core Concepts of OOP in JavaScript:

1. Encapsulation: Bundling data (properties) and methods (functions) that work on the data into a single unit, usually a class. It hides the internal details of the object and only exposes what’s necessary.

2. Abstraction: Hiding complex implementation details and showing only the necessary features to the user.

3. Inheritance: The mechanism by which one class can inherit properties and methods from another class, allowing for code reuse and a hierarchical class structure.

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Asynchronous Programming: Callbacks, Promises, and Async/Await

🔹 What is Synchronous in JavaScript?

Synchronous ka matlab hota hai — ek ke baad ek kaam hona.[sky- one by one]

Jaise ki:

Jab tak pehla kaam pura nahi hota, tab tak dusra start nahi hota.

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Immutable Deep Update using Nested Maps:

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🔁 Immutable Deep Update using Nested Maps

When working with nested data structures like arrays of objects (e.g., departments with employees), it's important to update values immutably — without modifying the original data.
This pattern uses nested .map() functions to update specific fields deep within the structure.

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### ✅ You can use `map()` on:

1. **An array of values**  
2. **An array of objects**  
3. **An array of arrays**  
Basically, any array.

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### 🔹 1. **Array of values**

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real-world data to show the difference between using map().flat() and flatMap().

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Scenario: A List of Orders and Items

You have an array of orders, and each order contains an array of items. You want to flatten the items from all orders into a single list.

1. Using map() and flat()

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Disable a Link Using Only CSS

Overview

This guide explains how to disable an anchor (<a>) link using only CSS, without JavaScript.

Example

We use the pointer-events: none; and color: gray; properties to visually and functionally disable the link.

HTML

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The Happy Number problem is about determining if a given number will eventually reach 1 by repeatedly replacing it with the sum of the squares of its digits. If the number reaches 1, it is called a happy number. Otherwise, if the process falls into a loop that does not include 1, the number is not happy.

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Steps of the Problem

1. Start with a positive integer n.
2. Replace n with the sum of the squares of its digits.
   • For example: If n = 19, compute ( 1^2 + 9^2 = 1 + 81 = 82 ).
3. Repeat the process:

• For ( n = 82 ): ( 8^2 + 2^2 = 64 + 4 = 68 ).

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1. Algorithm

   • Definition: A step-by-step set of instructions to solve a problem.
   • Example: A recipe for baking a cake is like an algorithm—it tells you what to do in sequence.

2. API (Application Programming Interface)

   • Definition: A way for different software systems to communicate.
   • Example: When you use Google Maps in a food delivery app, the app uses Google Maps' API to show directions.

3. Cloud Computing

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HTTP Methods in RESTful APIs (Elaborated)

RESTful APIs rely on standard HTTP methods to perform operations on resources. Here's an in-depth look:

1. GET (Retrieve Data)
   • Purpose: Fetch data from the server.
   • Characteristics:
     • Safe: It doesn't modify any data on the server.
     • Idempotent: Multiple identical requests return the same result.

• Example: