Today Learned in Java Script: Arrow Function,Map( ) Function,While Loop.

In JavaScript, an arrow function is a more concise way to write function expressions. Introduced in ES6 (ECMAScript 2015), arrow functions use the => syntax and have some differences compared to regular functions, especially in how they handle the this keyword.

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Basic Syntax

const add = (a, b) => a + b;

This is equivalent to:

function add(a, b) {
  return a + b;
}

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Key Features

1. Shorter syntax
2. Lexical this binding (doesn’t have its own this)
3. No arguments object (use rest parameters if needed)
4. Cannot be used as constructors (i.e., no new keyword)

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Key Point:

Arrow functions are shorter and do not have their own this value — they use the this from their surrounding code.

map() function in JavaScript:

The map() function is used to create a new array by applying a function to each element of an existing array.

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Syntax:

array.map(function(element, index, array) {
  // return new value for each element
});

• element – current item
• index (optional) – current item’s index
• array (optional) – the original array

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Example:

const numbers = [1, 2, 3, 4];
const doubled = numbers.map(num => num * 2);

console.log(doubled); // [2, 4, 6, 8]

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What map() Does:

• It does not change the original array.
• It returns a new array with transformed items.

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Common Use Cases:

• Modify array values
• Extract specific properties from objects
• Convert data formats

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### while Loop in JavaScript

The while loop is a control flow statement that allows code to be executed repeatedly based on a given condition.

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Syntax:

while (condition) {
  // code to run as long as condition is true
}

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Simple Example:

let i = 0;

while (i < 5) {
  console.log("Count:", i);
  i++;
}

Output:

Count: 0  
Count: 1  
Count: 2  
Count: 3  
Count: 4

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Key Points:

• The loop continues as long as the condition is true.
• Make sure to update the loop variable (i++ in the example), or it could become an infinite loop.
• Use break to exit early if needed.

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