Arrays

Array ek ordered, badli ja sakne wali collection hai — JavaScript mein Python ke list ka equivalent, aur shayad language mein sab se zyada istemal 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 bar-aks, 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 hata kar wapas 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 theek lag raha hai — lekin sort() asal mein elements ko strings mein convert kar ke unhe default tor par 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 waqai 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.