I want to show 'No URL' where url is not available ("") for any party. But that needs an indexing. Can someone please suggest how can I do the index to get the actual result

That works, but also, it's kinda going backwards.  a!forEach() is supposed to negate the need for almost any of the primitive looping functions (afaik the only one it can't directly replace is reduce()).  And for good reason - the primitive functions and partial evaluation are a nightmare for code readability and maintainability.