pnpm add https://github.com/JustAWaifuHunter/dtt.js
const { Biggest, BigMath } = require("dtt.js");
function fibonacci(size) {
let a = new Biggest(0),
b = new Biggest(1);
for (let i = BigInt(1); i < size; i++) {
[a, b] = [b, a.add(b)];
}
return a;
}
console.log(fibonacci(BigInt(10)).isReallyBiggest()); // false
console.log(fibonacci(BigMath.pow(10, 4)).isReallyBiggest()); // true