Is there a compelling reason for calling custom script? The scenarios that you mentioned can be achieved with OOTB configurations.

Further to Vikas' response - the short answer is yes PRPC can accomodate pretty much any custom javascript ....however , it is not [edit: oops, Thanks Eric for pointing this typo out] recommended to avoid using custom javascript as this could mean you are going 'outside the guardrails' - there can be no guarantee that any custom javascript will continue to work if you upgrade PRPC to a later version for instance.

With regard to getting a Javascript Exception - if the exception is unhandled , it leaves open the possibility of the UI becoming inoperable (usually cureable with an F5/Refresh) - but (generally) the back PRPC system has no way of knowing this, so (generally) the backend will not be able automatically 'carry-on' with any backend processing such as running a Data Transform.

What I mean is: is it possible to 'break' the UI using custom javascript ; which can only really be recovered by refreshing the front-end browser - and there is a risk of end-users losing their on-screen work.

This is not a outright 'ban' on using custom javascript ; but you shouldn't (we hope) need to resort to writing custom javascript for normal work processing - you should be able to 'glue' your application together using Designer-Studio, without ever having to 'go under the covers'....

May we ask what version of PRPC you are using ,and what is your general requirement here - it may be we can advise how to achieve what you want to do without having to use custom JS ?

Yes, I have a mandatory Script to call and I can't bypass that.