Date() in different timezone

This lib looks quite sane https://momentjs.com/timezone/ (MIT license). Is there a way to include something like that?

// hypothetical conversion for display of current time in different timezone
var now = moment(Date().toISOString())
now.tz('America/Los_Angeles').format('ha z');  // 5am PDT

For me js is still mystery so no idea where .format() in the above comes from...