Error while scanning and comparing values from a list

I have a method where I get an array. I'm trying to scan this array and compare it to a value of a variable.

    cnaeService.cnaes().then(function (result) {
        $scope.cnaes = result.data;
        vm.cnae = $scope.cnaes;
       var res = listCnae(vm.cnae);
        console.log(res);
    }, function (error) {
        if (error.status == 404) {
            $scope.error = 'Nenhum parametro foi encontrado.';
        }
        else {
            $scope.error = error.statusText;
        }
        });

    function listCnae(cnae) {
        for (var i = 0; i < $scope.cnaes; i++) {
            if (contribuinte.cnaes === $scope.cnaes.codigo) {
                $scope.descricao  =  contribuinte.descricao[i];
            } 
        }
    }

But it does not return anything to me.