Before we go too much further with Objects, we need to have a little talk about how those variables are stored in memory. Egads!, you say - but better now than later.

Say I create another one of those card objects:
var card1 = {"suit":"clubs", "rank": 8}

When I do this, I now have a variable card1 that points or 'refers' to the place in memory where the actual object data is stored. When I assign that variable to another variable, I'm really just creating another reference to that same place in memory.

So, if I create another variable called card2 and set it equal to the original card1.
var card2 = card1

I now have two variables pointing at the exact same data in memory. If I change a property in either variable, I change them both.