fibonacci using es6 generator

fibonacci.js

const fibonacci = {
    [Symbol.iterator]: function* () {
        yield 0;
        yield 1;
        let [pre, cur] = [0, 1];
        while (true) {
            [pre, cur] = [cur, pre + cur]
            yield cur;
        }
    }
}

for (const n of fibonacci) {
    if (n > 1000)
        break;
    console.log(n);
}