How does this generator returns 3?

Question

While trying to understand generator, instead of following:

function* powerSeries(number,power) {
 let base = number;
 while (true) {
 yield Math.pow(base, power);
 base++
 }
}
let n = powerSeries(3,2)
n.next() // value: 9
n.next() // value: 16
...

I tried like:

function* powerSeries(number,power) {
 let base = number;
 yield Math.pow(base, power);
 return base++ // was trying to understand what happens if using return
}
let n = powerSeries(3,2)
n.next() // value: 9
n.next() // value: 3 But how ????

I can understand post increment isn't being done because it's not inside a loop. So, it stays 3 for base. But how is it becoming 1 for power so it results in 3?

Acknowledged: Thank you everyone. I was confused that if I use return statement then it would still call yield.

• Sebastian Simon: You return base, not Math.pow(base, power) and base === 3. There is no power of 1; nothing is being exponentiated at the second .next.
• gulcy: Yeah, I'm knowingly doing that. And I already agree in my question that base is 3 as it's not inside loop. But how power is becoming 1?
• Sebastian Simon: Read my edited comment.
• Robin Zigmond: Why do you think power is becoming 1? It's still 2, but after the single yield statement (which produced the 9 you saw) it's never used again.
• Sebastian Simon: @gulcy "Ah, you mean yield is not being used but just return statement?" — Yes, of course. Why would yield be executed again? Try yield ["yield", Math.pow(base, power)]; return ["return", base++] instead. Do you see two yields? No; you get ["yield", 9] and ["return", 3].

Answer 1

From yield:

Description

[...]

A return statement is reached. In this case, execution of the generator ends and an IteratorResult is returned to the caller in which the value is the value specified by the return statement and done is true.

function* powerSeries(number,power) {
 let base = number;
 yield Math.pow(base, power);
 return base++ // was trying to understand what happens if using return
}
let n = powerSeries(3,2)
console.log(n.next().value); // 9
console.log(n.next().value); // 3
console.log(n.next().value); // undefined

• gulcy: Thanks. I get it fully now.