Form with onchange function

Question

I want to give option like pay by credit card or check.
If one select credit card in select option it opens credit card related form inputs/Check than check related form inputs before submiting form.
I would start like
<cfform action"" method=""Post>
<cfselect name="paymenttype" query="test" display="paymenttype" value="paymenttype">
<option value ="other">Other</>
</select>
<cfif form.paymenttype = "Credit Card">
<cfinput type="Test" name="creditcomp">
<cfelseif form.paymenttype = "check">
<cfinput type="text" name="bankinfo">
</cfif>
<input type="submit" value="Submit"></cfform>
I belive I need to use Java script onChange event but I never did Java script before, can any one help me on it?
I have been using cfcase and submiting form at each and than made session variable to generate appropriate result but now I wanrt to do some change.

Answer 1

For learning js, I recommend the book, Teach Yourself Javascript in 24 Hours.  It's how I learned.  There are also tutorials on webmonkey.
For what you are trying to do specifcally, I would put the credit card and bank stuff in separate divs and use js to show and hide them.  Google "javascript show hide"  to find code samples.