Authentication using for or filter ionic 3

Hello, I would like to know if I can use validation without without the configuration of the "Authentication" of FIREBASE, I have a list of objects,

if(placa == 'ABC123' && senha == '123')
   alert('logado')
else if(placa != 'ABC123')
   alert('placa errada')
else if (senha != '123')
   alert('senha incorreta')

Before, I get all the records in the DB, so I bring all the items I need

    getTrucks() {
    this.truckService.getTrucks()
          .subscribe(
            result => this.trucks = result
          )
  }

I've already tried using for and filter, but validation does not work using the

    filterTruck() {
    return this.trucks.filter((item) => {
      if(item.placa == this.truck.placa && item.password == this.truck.password) {
        console.log(item)
          this.navCtrl.setRoot('TabsPage');
          this.auth.authentication(true);
          this.auth.truckLogedd(user);
          return true;
      } else if(item.placa != this.truck.placa) {
        console.log('Placa não confere')        
          return false;
      } else if(item.senha != this.truck.senha) {
        console.log('Senhanão confere')        
          return false;
      }
      return false;
    })  
  }

Now, using the filter to try to validate

    filterTruck(users) {
    for(let user of users) {
      if(user.password != this.truck.password || user.placa != this.truck.placa) {
        this.showAlert('Ops!', 'Senha ou placa errada!')
        break;
      } else {
        this.navCtrl.setRoot('TabsPage');
        this.auth.authentication(true);
        this.auth.truckLogedd(user);
        break;
      }
    }
  }

I'm trying to do this validation without having to use the "Authentication" of the firebase, is it interesting to do so or using the same "Auhtentication"?