[tlug] When should an "onChange" event actually change?

[Dave M G <dave@example.com>]

TLUG,

Javascript type question here, though this might have to do with browser 
differences as well.

I've got a form that has text fields to enter in a username and 
password, and a submit button. I'm using Javascript to evaluate the 
content of the fields, to make the submit button be greyed out until 
certain criteria are met. For example, ensuring the text is more than 6 
characters and so on. When the two fields are filled in and pass all the 
criteria, the submit button turns green.

I use the "onChange" event to call the necessary functions that do the 
evaluating and change the button style properties.

Works basically fine. However, the timing is a little off. If I fill in 
both fields correctly, the button only turns green if I shift focus away 
from the text fields. So, I'll type in a user name, switch to the 
password field and type that in. When I type in the complete password, 
the button isn't green yet. If I click somewhere else on screen, *then* 
the button turns green.

It's as if "onChange" is behaving like what you might call a "mouse 
out", or an "onChangeOfFocus". I thought "onChange" mean whenever you 
changed the content of the text field.

It seems to me I've been to sites where the Javascript evaluates the 
content of a text field as it is typed.

Am I not understanding the expected "onChange" behaviour, or is it that 
I need to do something else, or in a addition, to get more immediate 
feedback from my Javascript?

Thank you for any advice.

--
Dave M G