fibonacci sequence with generators

fibonacci.js

function* fib () {
    var a = 0, b = 1, c;
    yield 0
    yield 1
    while (true) {
        c = b + a
        a = b
        b = c
        yield c
    }
}

var f = fib()

for (let i = 0; i < 7; i++) {
    console.log(f.next().value)
    // 0, 1, 1, 2, 3, 5, 8 ...
}