is there any way to import third party JS into mongoJS...?

Question

I am looking for a function to convert UTC timestamp to another timezone timestamp.

It needs two parameters,

utcTimestamp(1464891132) & timezoneString("Asia/Kolkata")

function convertToTimeZone(utcTimestamp, timezoneString) {
      //do some operations and  
    return "timestamp in given timezone";
}

I just checked link and found that there are some js libs, which solve that conversion problem, but now my problem is how can I import third party js to my mongoJS.

Or is there any patch or alternative to solve these problem in mongojs?

FYI I am using mongoJS from mongoshell....