Array Methods & Properties Kya Hote Hain?

JavaScript me Array ek built-in object hota hai jo ek collection of items store karne ke liye use hota hai. Ye items kisi bhi type ke ho sakte hain, jaise numbers, strings, objects, functions, etc.

JavaScript me arrays ke saath kaam karne ke liye bahut saare methods aur properties diye gaye hain jo hume elements ko manipulate karne, sort karne, filter karne, add/delete karne aur iterate karne ki suvidha dete hain.

JavaScript Array Properties :

Array properties arrays ke basic attributes ko define karti hain.

Property	Description (Vyakhya)
length	Array me total kitne elements hain, yeh batata hai.
constructor	Array object ka constructor function return karta hai.
prototype	Array prototype object ko access karne deta hai jisme methods aur properties hoti hain.

1. length Property :

JavaScript mein length ek property hai jo arrays, strings, ya objects ke elements ya characters ki total sankhya ko batati hai. Jab kisi array ya string ke saath use kiya jata hai, yeh uski total length return karta hai. Example ke roop mein, let arr = [1, 2, 3]; arr.length 3 return karega. Strings ke case mein, “Hello”.length 5 return karega. Yeh ek read-only property hai, par arrays ke case mein length ko modify karke elements ko remove bhi kiya ja sakta hai. Yeh property loops aur data manipulation ke liye bahut useful hoti hai.

let fruits = ["Apple", "Mango", "Banana"];
console.log(fruits.length); // Output: 3

2. constructor Property :

JavaScript me constructor property ek special property hoti hai jo kisi object ke constructor function ko refer karti hai. Ye property har object me automatically hoti hai aur us object ko banane wale function ka reference deti hai. Example ke liye, agar ek object new String(“Hello”) se banaya gaya hai, to obj.constructor === String hoga. Iska use mainly object ke type ko identify karne aur naye instances banane ke liye hota hai. Lekin, agar prototype chain modify ki jaye to ye property unreliable ho sakti hai. Isliye isko carefully use karna chahiye.

let arr = [1, 2, 3];
console.log(arr.constructor); // Output: function Array() { [native code] }

3. prototype Property :

JavaScript me prototype property ek built-in property hoti hai jo har function aur object ke saath aati hai. Jab hum kisi function ya object ko create karte hain, to JavaScript uske prototype mein ek default object attach kar deta hai. Yeh property inheritance ko enable karti hai, jisse ek object dusre object ke properties aur methods access kar sakta hai. Prototype chaining ke through hum ek object ke andar naye methods aur properties add kar sakte hain, jo uske sabhi instances ke liye accessible hote hain. Yeh JavaScript mein memory efficient aur reusable code likhne ke liye useful hota hai.

Array.prototype.newMethod = function() {
console.log("Yeh naya method hai!");
};
let arr = [1, 2, 3];
arr.newMethod(); // Output: Yeh naya method hai!

JavaScript Array Methods :

JavaScript me array ke saath kaam karne ke liye bahut saare methods hote hain, jo alag-alag tasks ke liye use kiye jate hain.

1. Adding & Removing Elements (Add/Delete Methods)

push() :

push() ek JavaScript array method hai jo kisi array ke end mein ek ya ek se zyada elements add karta hai aur naye array ki length return karta hai. Yeh method original array ko modify karta hai, yani mutable hota hai.

pop() :

pop() JavaScript me ek array method hai jo last element ko remove karta hai aur us removed element ko return karta hai. Ye method original array ko modify karta hai, yani ki last element ko permanently hata deta hai. Empty array par use karne par undefined return hota hai.

unshift() :

unshift() ek JavaScript array method hai jo ek ya ek se zyada elements ko array ke beginning me add karta hai aur naye length ko return karta hai. Yeh existing elements ko right shift karta hai, bina kisi element ko delete kiye.

shift() :

shift() ek JavaScript array method hai jo array ke first element ko remove kar deta hai aur us element ko return karta hai. Yeh method original array ko modify karta hai, jisse uski length ek value se kam ho jati hai.

 let numbers = [10, 20, 30];
numbers.push(40);
console.log(numbers); // Output: [10, 20, 30, 40]

numbers.pop();
console.log(numbers); // Output: [10, 20, 30]

 let colors = ["Red", "Green"];
colors.unshift("Blue");
console.log(colors); // Output: ["Blue", "Red", "Green"]

colors.shift();
console.log(colors); // Output: ["Red", "Green"]

2. Joining & Splitting Arrays :

join() :

join() JavaScript ka ek method hai jo array ke sabhi elements ko ek single string me convert karta hai, specified separator ke saath. Default separator comma (,) hota hai, lekin custom separator bhi diya ja sakta hai.

split() :

split() JavaScript ka ek method hai jo string ko ek specified separator ke basis par tod kar ek array me convert karta hai. Agar separator na diya jaye, to pura string ek single-element array me return hota hai.

let fruits = ["Apple", "Banana", "Mango"];
let result = fruits.join(", ");
console.log(result); // Output: Apple, Banana, Mango

let text = "Hello World! Welcome to JavaScript.";
let wordsArray = text.split(" ");
console.log(wordsArray);
// Output: ["Hello", "World!", "Welcome", "to", "JavaScript."]

3. Searching Methods :

indexOf() :

indexOf() ek JavaScript method hai jo kisi string ya array me kisi specific element ya substring ka pehla occurrence dhundhne ke liye use hoti hai. Agar element milta hai to uska index return hota hai, warna -1 return hota hai.

lastIndexOf() :

lastIndexOf() JavaScript me ek method hai jo kisi string ya array me ek specified value ka last occurrence (aakhri baar aane wali position) return karti hai. Agar value nahi milti, to yeh -1 return karti hai. Indexing zero-based hoti hai.

includes() :

JavaScript includes() ek array ya string ka method hai jo check karta hai ki koi specific value usme exist karti hai ya nahi. Yeh true return karta hai agar value milti hai, nahi toh false. Case-sensitive hota hai aur partial match support nahi karta.

let fruits = ["seb", "kela", "anar", "kela", "aam"];

console.log(fruits.indexOf("kela"));
// Output: 1 (pehla "kela" index 1 par hai)

console.log(fruits.lastIndexOf("kela"));
// Output: 3 (aakhri "kela" index 3 par hai)

console.log(fruits.includes("anar"));
// Output: true ("anar" array me maujood hai)

console.log(fruits.includes("angoor"));
// Output: false ("angoor" array me nahi hai)

4. Extracting & Manipulating Arrays :

slice() :

slice(start, end) method array ka ek portion return karta hai bina original array ko badle. Ye start index se lekar end index tak (end exclusive) ka data nikalta hai.

splice() :

splice(start, deleteCount, item1, item2, …) method array me elements ko add, remove ya replace karta hai. Ye original array ko modify karta hai.

let fruits = ["seb", "kela", "anar", "aam", "angoor"];

// slice() Example
let slicedFruits = fruits.slice(1, 4);
console.log(slicedFruits); // Output: ["kela", "anar", "aam"]

// splice() Example
fruits.splice(2, 1, "papita", "tarbooj");
console.log(fruits); // Output: ["seb", "kela", "papita", "tarbooj", "aam", "angoor"]

5. Sorting & Reversing :

sort() :

sort() method array ke elements ko ascending order me arrange karta hai. Default sorting strings ke hisaab se hoti hai.

reverse() :

reverse() method array ke order ko ulta kar deta hai, yani pehle element ko last aur last element ko pehle kar deta hai.

let numbers = [4, 2, 9, 1, 5];

numbers.sort();
console.log(numbers);
// Output: [1, 2, 4, 5, 9] (ascending order me sort ho gaya)

numbers.reverse();
console.log(numbers);
// Output: [9, 5, 4, 2, 1] (order ulta ho gaya)

6. Iterating (Looping) Methods :

forEach()

Yeh method array ke har ek element ke liye ek function execute karta hai, lekin koi naya array return nahi karta. Yeh sirf iteration ke liye use hota hai, jismein hum har element par koi operation perform kar sakte hain, jaise console par print karna ya kisi aur logic ko apply karna.

map() :

Yeh method array ke har element par ek function apply karta hai aur ek naya array return karta hai. Jo bhi transformation ya modification karni ho, woh map() method se ki ja sakti hai bina original array ko change kiye.

filter() :

Yeh method ek naya array return karta hai, lekin sirf un elements ko rakhta hai jo di gayi condition satisfy karte hain. Agar kisi element par condition false ho jaye, toh woh naye array me include nahi hota. Yeh filtering ke liye kaafi useful hai.

reduce() :

Yeh method saare elements ko combine karke ek single value return karta hai. Iska use sum, multiplication, maximum ya kisi bhi aggregated value ko nikalne ke liye kiya jata hai. Isme ek accumulator hota hai jo har iteration me updated value store karta hai.

let numbers = [1, 2, 3, 4, 5];

// forEach(): sirf har element ko print karega
numbers.forEach(num => console.log(num * 2));
// Output: 2, 4, 6, 8, 10

// map(): har element ka square karke naya array return karega
let squares = numbers.map(num => num * num);
console.log(squares);
// Output: [1, 4, 9, 16, 25]

// filter(): sirf even numbers ka naya array banayega
let evens = numbers.filter(num => num % 2 === 0);
console.log(evens);
// Output: [2, 4]

// reduce(): sabhi numbers ka sum return karega
let sum = numbers.reduce((acc, num) => acc + num, 0);
console.log(sum);
// Output: 15

JavaScript me array ke saath kaam karne ke liye bahut saare methods aur properties available hain jo hume elements ko modify, search, sort, filter aur manipulate karne me madad karte hain.

Quiz: Test Your Knowledge on JavaScript Array Methods & Properties

Bonus: Practical Application!

Aaj hi apne JavaScript code me array methods & properties ka istemal karke dekhein!

JavaScript arrays ko sahi tareeke se samajhne ke liye different methods jaise push(), pop(), shift(), unshift(), map(), filter(), reduce(), forEach(), aur properties jaise length ka upayog karein aur apne coding skills ko aur bhi improve karein.