Fibonacci sequence implemented as ES6 generator (works in Firefox console and Node v 0.12 w/harmony)

fibonacci.js

function *fibonacci() {
  var curr = 1
    , last = 0
    , x;

  yield 1;

  while (true) {
    x = last + curr;
    last = curr;
    yield curr = x;
  }
}

var fib = fibonacci();

console.log(fib.next().value); //returns 1
console.log(fib.next().value); //returns 1
console.log(fib.next().value); //returns 2