You can use rules with fields in collections. Let me know what you're trying to do and maybe I can help sort out the issues you're experiencing.

you need to use a hyphen. Say the field is Field 32, then you refer to it in Javascript as '#Field32-0' or '#Field32-1' if you have it set to a specific amount of amount of items.

Now, if it's a collection with an unknown amount, try having your javascript like this:

$('[id^=Field32]').each(function(){
        //Code here
    });
    

Basically, your JavaScript needs to target each of the repeatable collections that can appear. Here's some code that should work with the classes you specified.

$(document).ready(function () {
    $('.cf-collection-block').on('change', showhide);

    function showhide() {
        $('.cf-collection-block ul').each(function () {

            if ($(this).find('.OptionsCheck input:checked').val() == 'ADF') {
                $(this).find('.ADF').hide();
            }
            else {
                $(this).find('.ADF').show();
            }
        });

    }
});

So, instead of finding all of the ADF fields and hiding them, we're only finding the ones in the appropriate repeated collection of fields.
 

Hi Eric, this works great for what I was after! - I just need to swap the show/hides as I wanted it to display the field when the checkbox is checked.

This leads me to another question now though (I'm sorry)! I wanted to use field rules as you know to show the fields when the boxes were ticked, therefore I was hoping to keep the fields hidden in the collections on page load. Even though I have used the following:

  $(".ADF").hide();

at the start of my JavaScript, the fields in added collections are still visible to start with. Is there a bit of code I need to add to tell it to apply for all?

Also, the code posted works only for one checkbox to display it's field - could this work for multiple? 

Let's say I had check box ADF and FAX, both having 2 fields each. Is it possible to write JavaScript so that if I also wanted to display the FAX fields when checked I could do?

If you want to have the fields hidden at the beginning, you'll want to use CSS to hide the fields initially. Try the following CSS rule:

.ADF {display:none;}

As for your second question, you could copy the code above and change OptionsCheck and ADF to the relevant classes and it should work.

Hi Eric,

I managed to get the other check boxes doing what I had initially planned doing something similar to what you mentioned.

I'm unable to use {display:none;} because the fields are side-by-side - using the {display:inline-block;}. Things just get trickier and trickier!  I will continue to investigate possible options, thanks for all the help!