checkboxlist & client side script

[sdoerfli]

hi,

i have a website with a checkboxlist where onclick of a special item
of it a highlighting of an object in a map should be performed.
my problem is that i could call a javascript on client side with the
onclick attribute, but i need to iterate over all items of the
checkboxlist. so, how can i get the number of all items in the
checkboxlist on client side???
i need to perform the action (highlighting on map) on server side.

thx