Making a template helper reactive in Meteor

Question

I am building a chat application and on my \"new chats\" page I have a list of contacts, which you can select one by one by tapping them (upon which I apply a CSS selected class

Answer 1

To mimick the behaviour of Session without polluting the Session, use a ReactiveVar:

 Template.contactsLayout.created = function() {
      this.data.newChatters = new ReactiveVar([]);
 }

 Template.contactsLayout.events({
      'click #contactItem': function (event, template) {
            ...
            template.data.newChatters.set(
                template.data.newChatters.get().push(this.username)
            );
           ...

Then, in the inner template, use the parent reactive data source:

 Template.newChatDetails.helpers({
      newChatters: function() {
           return Template.parentData(1).newChatters.get();
      }
 });