Fixed version

index.js

console.time("Node Loop Benchmark");

import Long from "long";

let sum = Long.ZERO;
for (let i = 0; i < 1_000_000_000; i++) {
    sum = sum.add(Long.fromInt(i)); // more efficient for small values
}
console.log("Sum:", sum.toString());
console.timeEnd("Node Loop Benchmark");