version(170);

function fib() {
  var i = 0, j = 1;
  while (true) {
    yield i;
    var t = i;
    i = j;
    j += t;
  }
}

var g = fib();
for (var i = 0; i < 10; i++) {
  print(g.next() + "\n");
}

$ js fibor2.js
fibor2.js:6: SyntaxError: missing ; before statement:
fibor2.js:6:     yield i;
fibor2.js:6: ..........^