yield

gistfile1.js

function simpleGenerator(){
  yield "first";
  yield "second";
  yield "third";
  for (var i = 0; i < 3; i++)
    yield i;
}
 
var g = simpleGenerator();
console.log(g.next()); // "first"
console.log(g.next()); // "second"
console.log(g.next()); // "third"
console.log(g.next()); // 0
console.log(g.next()); // 1
console.log(g.next()); // 2
console.log(g.next()); // StopIteration