Arrays

Array ek ordered, changeable collection hai — JavaScript mein Python ke list ka equivalent, aur shayad language mein sabse zyada use hone wala data structure.

let fruits = ["apple", "banana", "cherry"];
console.log(fruits);
console.log(fruits[0]);
console.log(fruits[fruits.length - 1]);

fruits.push("date");
console.log(fruits);

fruits.pop();
console.log(fruits);

console.log(fruits.length);

[ 'apple', 'banana', 'cherry' ]
apple
cherry
[ 'apple', 'banana', 'cherry', 'date' ]
[ 'apple', 'banana', 'cherry' ]
3

• fruits[0] pehla item deta hai — Python ke ulat, JavaScript mein negative indexing nahi hoti, isliye fruits[fruits.length - 1] se last item milta hai
• push() array ke end mein ek item add karta hai, in place
• pop() last item ko remove karke return karta hai
• length ek property hai jo hamesha array ka current size batati hai

Sorting — aur ek real gotcha

let numbers = [5, 3, 1, 4, 2];
numbers.sort();
console.log(numbers);
numbers.reverse();
console.log(numbers);

[ 1, 2, 3, 4, 5 ]
[ 5, 4, 3, 2, 1 ]

Yeh sahi lag raha hai — lekin sort() actually elements ko strings mein convert karke unhe default roop mein alphabetically compare karta hai, jo single digits ke liye sahi order de deta hai. Jaise hi koi number ek se zyada digit ka hota hai, yeh toot jaata hai:

let bigNumbers = [10, 1, 21, 2];
bigNumbers.sort();
console.log(bigNumbers);

[ 1, 10, 2, 21 ]

"10" alphabetically "2" se pehle aata hai, bilkul waise hi jaise "apple" "banana" se pehle aata hai — yahi genuinely yahan hua hai. Numbers ko sahi se sort karne ke liye, ek comparator function do: numbers.sort((a, b) => a - b).

Aage: objects — values ko position ke bajaye naam se store karna.