Params isn't cleared between requests?



I just noticed that the params hash isn’t being cleared between
invocations, at least in an Ajax scenario I got into, or at least
behaved very strange.

I have an observer on a checkbox which sends its value as it is changed.

First click sent value=1 and arrived into params with value=1
Second click sent value=undefined and arrived into params with value=1
(instead of undefined which was in the POST data).

If in the controller after using the params[:value] I deleted the :value
param then the POST data would arrive just fine.

Any explanation how can this be?