TruClient - Parameters - How to add an incrementor in scripting

I want to create multiple file like Test1, test 2, test 3 etc

var currentDate =d.getFullYear().toString()+ ('0' + m).slice(-2).toString()+ ('0' + d.getDate()).slice(-2).toString();
var currentTime = ('0' + d.getHours()).slice(-2).toString() +('0' + d.getMinutes()).slice(-2).toString() +('0' + d.getSeconds()).slice(-2).toString();
var parameterName="Test_" + currentDate + "_"+ currentTime

This sometimes creating with same date n time also . I want to add an incrementor whenver it  generates.

like Test_1_CurrentDate:CurrentTime

could anyone suggest me how to add an incrementor