Why Array Map function not works

Hi,

I tested the following script on browsers (changed gs.print to console.log), it was okay. However, it returned error on ServiceNow when I tried to run it in Background Script. It seems that Array Map function is not working. Anyone knows why?

The Script:

var keywords = ['A', 'B', 'C'];

var parts_name = keywords.map(function (item) {return item + '; ';});

gs.print(parts_name[0], parts_name[1], parts_name[2]);

The error returned:

Javascript compiler exception: The undefined value has no properties. (<refname>; line 3) in:

var keywords = ['A', 'B', 'C'];

var parts_name = keywords.map(function (item) {return item + '; ';});

gs.print(parts_name[0], parts_name[1], parts_name[2]);

Thank you very much,

Eric Poon