How to write client script for below

[samba siva redd]

1. In "HR Planning & Operation" table i have two reference fields called 'Category' & 'Subcategory'.

2. While creating Category and Subcategory records i have a checkbox called "Allow approver user". I will create by making true that check box.

3. When i create a records in "HR Planning & Operations" table i will select "Category and Subcategory" which is the checkbox is true.

4. After selecting "Category & Subcategory" Then the new field "Approver" in should be visible HR planning& Operation table .

[Mark Manders]

Is it just showing up when (sub)category is selected, or is it conditional on what is selected? 

Not sure why you want a client script for this. A UI policy would do.

[samba siva redd]

I have Tried UI Policy, But No Luck.
When i selected both Category and Subcategory. Without Selecting Category we cannot select Subcategory Directly. Subcategory is dependent table of Category Table.

[Mark Manders]

That still only answers half. What didn't work for your ui policy.

if category = abc and subcategory = xyz, show field. That should just work.

[samba siva redd]

I have dot walked through Show related fields in UI Policy condition. But it was not worked.