use JavaScript::V8;

...

my $vectorjs = slurpBinFile('sylvester.js');
my $strandbeestjs = slurpBinFile('strandbeest.js');
my $js = $vectorjs . ' ' . $strandbeestjs;

...

    my $ok = -1;
    my $errortype = 'MATH_ERROR';
    my %scores;
    
    my $ctx = JavaScript::V8::Context->new();
    $ctx->bind_function(write => sub { print @_ });
    $ctx->bind_function(setFailed => sub { 
                                          $ok = 0;
                                          $errortype = shift @_;
                                          });
    $ctx->bind_function(setFinished => sub { 
                                          $ok = 1;
                                          %scores = @_;
                                          });
    
    $ctx->bind(params => \%params);
    
    $ctx->eval($js);
    my $error = $@;
    my $total = -1000; # Default: Failed!
    if(defined($error)) {
        print("SCRIPT ERROR: $error\n");
    } elsif($ok == -1) {
        print("Script didn't call setFailed() or setFinished()\n");
    }

...