gistfile1.handlebars

<template name="joinedRoomsList">
  <select id="joined-rooms">
    {{#each joinedRooms}}
      <option>{{name}}</option>
    {{/each}}
  </select>
</template>

gistfile2.js

  Template.body.helpers({
    joinedRooms: function () {
      console.log("in joinedRooms"); // does not appear in console.
      return Rooms.find({joinedUsers: Meteor.userId()}); // works in client console
    }
  });