Array Methods: map, filter, aur reduce

map() aur filter() bilkul JavaScript ki tarah kaam karte hain, lekin TypeScript transformation ke through type ko track karta hai — ek number[] ko ek aise function se map karo jo string wapas karta hai, aur result string[] ke tor par infer ho jaata hai, koi annotation ki zaroorat nahi.

const numbers: number[] = [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 ]

reduce — har item ko ek value mein jorna

reduce() ek accumulator ko ek item se doosre tak le jaata hai. TypeScript accumulator ka type us shuruati value se infer karta hai jo aap dete hain.

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

15

Aage: exception handling — errors ko pakarna, aur ek caught error unknown type ka kyun hota hai, any nahi.