Dmitry S. Dmitry S. - 3 months ago 39
Node.js Question

Javascript yield from the function nested inside generator

This code generates an error:

function *giveNumbers() {
[1, 2, 3].forEach(function(item) {
yield item;
})
}


This is probably because yield is inside a function that is not a generator. Is there an elegant way to overcome this? I mean other than:

function *giveNumbers() {
let list = [1, 2, 3];
for (let i = 0; i < list.length; i++) {
yield list[i];
}
}

Answer

This is probably because yield is inside a function that is not a generator.

Yes. You cannot use yield from callbacks.

Is there an elegant way to overcome this?

Depends on the use case. Usually there is zero reason to actually want to yield from a callback.

In your case, you want a for…of loop, which is superior to .forEach in almost every aspect anyway:

function *giveNumbers() {
    for (let item of [1, 2, 3])
        yield item;
}