Meteor : call javascript function when there's new data on server

I was soo tired just searching about this, believe me I literally read all posts on stackoverflow regarding those keywords
What I wanna do?

Simple, there's this javascript function on client side that adds some elements to the DOM
It get the data from a data source at the server. But I want this data source to be reactive, so that when ever someother user make a change that data source, all the clients connected should feel that change through the said javascript function.

Here's the code