Interview question

What is destructuring in JavaScript and how does it work for arrays and objects? JavaScript में destructuring क्या है और arrays व objects के लिए कैसे काम करता है?

Answer

Destructuring is a concise syntax for extracting values from arrays or properties from objects into individual variables.

// Array destructuring
const colors = ['red', 'green', 'blue'];
const [first, second, third] = colors;
console.log(first, second, third); // red green blue

// Skipping elements
const [primary, , tertiary] = colors;
console.log(primary, tertiary); // red blue

// Default values
const [a = 'default1', b = 'default2'] = ['custom'];
console.log(a, b); // custom default2

// Swapping variables without a temp variable
let x = 1, y = 2;
[x, y] = [y, x];
console.log(x, y); // 2 1

// Object destructuring
const user = { name: 'John', age: 30, city: 'NYC' };
const { name, age } = user;
console.log(name, age); // John 30

// Renaming while destructuring
const { name: userName, age: userAge } = user;
console.log(userName, userAge); // John 30

// Default values for objects
const { country = 'USA' } = user;
console.log(country); // USA - property doesn't exist, uses default

// Nested destructuring
const company = { name: 'Tech Corp', address: { city: 'SF', zip: '94000' } };
const { address: { city, zip } } = company;
console.log(city, zip); // SF 94000

// Destructuring in function parameters
function greet({ name, age }) {
    console.log(`${name} is ${age} years old`);
}
greet(user); // John is 30 years old

Destructuring arrays से values या objects से properties निकालकर individual variables में डालने का concise syntax है।

// Array destructuring
const colors = ['red', 'green', 'blue'];
const [first, second, third] = colors;
console.log(first, second, third); // red green blue

// Elements skip करना
const [primary, , tertiary] = colors;
console.log(primary, tertiary); // red blue

// Default values
const [a = 'default1', b = 'default2'] = ['custom'];
console.log(a, b); // custom default2

// Temp variable के बिना swap करना
let x = 1, y = 2;
[x, y] = [y, x];
console.log(x, y); // 2 1

// Object destructuring
const user = { name: 'John', age: 30, city: 'NYC' };
const { name, age } = user;

// Rename करना
const { name: userName, age: userAge } = user;

// Default values
const { country = 'USA' } = user;
console.log(country); // USA

// Nested destructuring
const company = { name: 'Tech Corp', address: { city: 'SF', zip: '94000' } };
const { address: { city, zip } } = company;

// Function parameters में destructuring
function greet({ name, age }) {
    console.log(`${name} is ${age} years old`);
}
greet(user);

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