1function* idMaker() {
2  var index = 0;
3  while (true)
4    yield index++;
5}
6
7var gen = idMaker();
8
9console.log(gen.next().value); // 0
10console.log(gen.next().value); // 1
11console.log(gen.next().value); // 2
12console.log(gen.next().value); // 3
13// ...

1function* g(){    //or function *g(){}
2  console.log("First");
3  yield 1;
4  console.log("second");
5   yield 2;
6  console.log("third");
7} 
8let generator=g();
9generator.next();
10generator.next();

1function* name([param[, param[, ... param]]]) {
2   statements
3}
4

1function* makeRangeIterator(start = 0, end = 100, step = 1) {
2    let iterationCount = 0;
3    for (let i = start; i < end; i += step) {
4        iterationCount++;
5        yield i;
6    }
7    return iterationCount;
8}