How to handle the if-else in promise then?

Question

In some case, when I get a return value from a promise object, I need to start two different then() precesses depend on the value\'s condition, like:

Answer 1

This is how I did it in my fetch() I am not sure if this is the right way, but it works

 fetch().then(res => res.ok ? res : false).then(res => {
    if (res) {
        //res ok
    } else {
       //res not ok
    }

});