Convert PHP echoed date to client local time

Convert PHP echoed date to client local time

This is my first post. I have a problem that i can't seem to resolve. Here
it goes:
I have a PHP script that prints the date of an event to the page:
$event_datetime = date("g:i A (m/d/y)", strtotime($row['event_time']));
echo $event_datetime
I want to use Javascript to convert that $event_datetime into client local
timezone preferably or local client computer time.
Any ideas ?
Thanks in advance !