Generator without yield

Question

var A = {
 demo : function() * {
 /* Some logic here, but no yield is used */
 } 
}

What is the use of a generator method that does not yield anything? Have you ever used something like this? What was the use case?

• Felix Kling: Maybe whatever calls demo expects an iterator to be returned. A generator function is a simple way to create an iterator.
• Alkis Kalogeris: Yes that's a good use case. Have you ever used for any other cases?
• Alkis Kalogeris: @FelixKling If you want you can post your comment as an answer so I can accept it.

Answer 1

It's quite the same case like an empty function - someone wants to call a function, but you have nothing to do.

Similarly, an empty generator function is a function which creates a generator that does nothing. It does represent the empty sequence. However, a generator function that doesn't yield isn't necessarily empty - it can still do something and have a result value, but there simply are no intermediate results.

Answer 2

The following code prints 'someValue' on the response every 100 ms for 5 seconds. It does not use yield.

const Koa = require('koa');
const through = require('through');
(new Koa()).use(function *(){
 const tr = through();
 setInterval(() => tr.write('someValue\n'), 100);
 setTimeout(tr.end, 5000);
 this.body = tr;
}).listen(3003, () => {});

Access with: curl localhost:3003