If-Then-Else Mapping using Scripting Functoid

i have been using isNil,equal, Logical OR , NOT,value Mapping and string concat functoid to achieve the IF-Then-Else condition in biztalk map. it doesn't give me full solution so i need to use scripting functoid for the same.

Scenario

I have 4 parameters(param1,param2,param3,param4) in the source and one field in the destination which has a concatenated value with OR (param1 OR param2 OR param3 OR param4). the problem is if one of the parameter is null the destination has no value at all.

can anyone tell help me how to do the same in scripting functoid.

Jeseena