Help with rjs (basic)

I have a rjs with:

page.replace_html 'tag', '<input name="abc" id="abc" value="avalue">' +
link_to_remote("doit", :url =>{ :action => :doit })

how I read the value of the "abc" field in the :doit remote action
after the user click on the doit link?

Thanks

The answer was to use prototype's $F() function which returns the
value of any field input control:

page.replace_html 'tag', '<input name="abc" id="abc" value="'+@tag+'">'
+ link_to_remote( "doit", :url =>{ :action => :doit }, :with =>
"'abc='+$F('abc')" )