I've created a reproduction here.
The Meteor release for this bug is 1.2.1. This bug is not present in the latest release of 1.3.4.
After creating the project with meteor create, I removed insecure and autopublish and added reactive-var.
I'm using Mac OS X El Capitan and Chrome version 51.0.2704.103 (64-bit).
When passing the result of a ReactiveVar's .get() to Template.instance().subscribe as an argument, the ReactiveVar's value is set to the subscription's handle. (I'm assuming it's the subscription handle based on the onStop function but I haven't done thorough investigation.)
Passing an object as a parameter to a subscribe function should not change the object.
Example: this.subscribe("helloSub", this.query.get());
git clone https://github.com/mokolodi1/reactivevar-subscribe-bug
cd reactivevar-subscribe-bug
meteor
open http://localhost:3000/Hello = new Meteor.Collection("hello");
if (Meteor.isClient) {
Template.body.onCreated(function() {
this.query = new ReactiveVar({});
console.log("query before:", this.query.get());
console.log("Object.keys(this.query.get()):", Object.keys(this.query.get()));
this.subscribe("helloSub", this.query.get());
// NOTE: this.query.get() should still be {}
console.log("query after:", this.query.get());
console.log("Object.keys(this.query.get()):", Object.keys(this.query.get()));
});
}
if (Meteor.isServer) {
Meteor.publish("helloSub", function(query) {
return Hello.find(query);
});
}