# Set up values to be tested
    ...
    $mech->field( $name => $value );
    ...

    my ($value, $type) = $mech->eval_in_page('validateIpSettings()');
    is($value, 'some expected value');

##</code><code>##

    # create myalert as Javascript function
    my $myalert = $mech->declare(<<JS);
function (msg) {};
JS

    my ($value, $type) = $mech->eval_in_page('validateIpSettings()', { alert => $myalert });