I use data api, to change my object, so that I can take advantage of changeData and setData event.

for example,

var customer = { name : "john" };

instead of change customer like

customer.name = "tim",

I use

$(customer).data("name", "tim");

so that I can use the event to handle the data change. In jQuery 1.4.4 , I can assert

customer.name == "tim",

but in 1.5, the behavior has change, it is now using the jQuery.cache object as like other objects,

here is a dump, of the customer.

Customer

1. jQuery1297093665961: 37

2. name: "john"

3. __proto__: Object

jQuery.Cache

1. 37: Object

1. name: "tim"

I am not sure reason of the change, but it break my code, possibly of many others. But the release note of 1.5 does not mention about the change, although, the change does pass the unit test, but it break user's expectation of the its side effect.