Promises chaining

Question

I am begining in node and I have a problem, I need to do this only with promises by node versions, I need to make a comparison with the result of previous promises but dont works, it seems me that is code that is poorly structured, here the code thanks...

ListarUsuariosMaxDate.then(response => {
    return ListaconCondicionProceso(response);
}).then(data2 => {
    return filtrarPagos.then(data3 => {

            let result = data3.filter(elem => data2.filter(elem2 => elem.user == elem2.user_id && elem.createdAt > elem2.maximo).length > 0);

            return result;

        }).then(data5 => {

            console.log(data5)

        })

    })


})

the result (data5) is emtpy...sorry about the mistake...

Answer 1

I could do it something change and works, but I don't understand why. I had in my previous code with async and await this structure, and it worked:

  async function comparacionTotalProceso(listaTotal, listaFiltrada) {


            let result = listaFiltrada.filter(elem => listaTotal.filter(elem2 => elem.user == elem2.user_id && elem.createdAt > elem2.maximo).length > 0);

            return result;
        });
    }

but now for node version, I need to change everything to promises and I did this:

...

.then(data2 => {
        return filtrarPagos.then(data3 => {

            let result = data2.map(elem => data3.map(elem2 => elem.user == elem2.user_id && elem.createdAt > elem2.maximo).length > 0? elem:null);

            return result;

        })

and finally works changed the filter for map and return elem, but I don't know why.