What does this generator syntax do?

Question

What does the following syntax mean? I don’t understand the use of a * after a yield. I’m new to generators, redux, and sagas, so I would appreciate some help understanding what the syntax *, takeEvery(), and the return function *(action) { do:

var MIDDLEWARES = []

function builder( ) {
    const LOAD_DATA = "POI_LOADER/LOAD_POIS"
    MIDDLEWARES.push( function *sagaFunction() {
        yield *takeEvery( LOAD_DATA, loadData( statusField) )
    } )
}

const loadData = (statusField) => {
    return function *(action) {
        console.log("action.venueId = " + action.venueId)
    }
}

There are several questions here:

1. What does the * in yield *takeEvery() mean? Seems to be answered by Delegated yield (yield star, yield *) in generator functions.
2. Why doesn't the builder() function need a * to make it a generator given that it contains a yield * statement? Is that because the yield *takeEvery() is wrapped in the generator function sagaFunction()?
3. What does the takeEvery() function do, especially given that it has a * in front of it? I think takeEvery(). Based on its documentation, I think it applies loadData() to everything in LOAD_DATA. But if LOAD_DATA isn't an array, is takeEvery() needed in this code?
4. How come the declaration return function *(action) seems to have no name for the function? Is it declaring a generator with input parameter action and assigning that generator for a const called loadData?
5. Does the Saga library call next() on the generators created in this code?

Answer 1

So generators allow to return a value from a generator function by using yield and then resume execution from there on the next call.

yield* is used to indicate that the value returned is coming from another generator - so the generator function that calls yield* is delegating the actual value creation to another generator function in this case.

See MDN on this for more info.