The HTML 4.01 Specification says this about the onchange event:
"The onchange event occurs when a control loses the input focus and its value has been modified since gaining focus. This attribute applies to the following elements: INPUT, SELECT, and TEXTAREA."
Okay. Well currently Firefox doesn't follow this (at least for radio buttons), but instead does something outrageous; it fires an onchange event if something changes, for example, if the radio button checked state changes. (Although I hear it "correctly" fires onchange for a text input only when it loses focus; perhaps to avoid the event noise that would occur during text entry).
Sarcasm aside, I imagine there are good reasons for the HTML Specification but I can't help but think, at least in the post submit-page-refresh model of web development, that we could stand to have a more immediate onchange event, perhaps called onvaluechange?
Some hacky vanilla test code is in my exploratory. Yes, I've taken a liking to using the word exploratory as a noun.