yield
function* F1(){
var x = 0;
for (let i = 0; i < 10; i++){
yield x++;
}
}
var gen = F1();
gen.next();
gen.next();
console.log(gen.next().value); // 2
function* F1(){
var x = 0;
for (let i = 0; i < 10; i++){
yield x++;
}
}
var gen = F1();
gen.next();
gen.next();
console.log(gen.next().value); // 2