Array Methods: map, filter, aur reduce

map() aur filter() woh do array methods hain jo aap baar baar use karoge — zyada tar Python developers bilkul isi tarah ke transformation ke liye list comprehensions use karte hain, aur yeh JavaScript ka equivalent hain.

const numbers = [1, 2, 3, 4, 5];
const squared = numbers.map((x) => x * x);
console.log(squared);

const evens = numbers.filter((x) => x % 2 === 0);
console.log(evens);

[ 1, 4, 9, 16, 25 ]
[ 2, 4 ]

map() har item ko transform karta hai aur same length ka naya array return karta hai. filter() sirf woh items rakhta hai jinke liye function true return karta hai, isliye result original se chhota ho sakta hai. Dono mein se koi bhi original array ko change nahi karta.

reduce — har item ko ek value mein combine karna

const numbers = [1, 2, 3, 4, 5];
const total = numbers.reduce((sum, x) => sum + x, 0);
console.log(total);

15

reduce() array mein se guzarta hai, ek accumulator (sum) ko ek item se doosre tak carry karte hue. 0 accumulator ki starting value hai. Yahan yeh bas sab kuch add kar raha hai, lekin reduce() array se koi bhi single result bana sakta hai — ek total, ek maximum, ya ek poora naya object bhi.

Aage: exception handling — apne program ko crash hone dene ke bajaye errors ko sahi tareeqe se handle karna.