Access Application or Flow level variables through java script in VBCS

Summary

Access and manipulate Application or Flow level variables through java script in VBCS

Content

I have added few variables at application leven and flow level with session scope. I want to access or manipulate that variable values through my JS code in order in avoid writing the same code again and again. 

For example: I am calling the rest endpoint in my action chain and I have set the parameters of that rest endpoint in those variables. Now i want to reuse the existing action chain with different paramters. One option is to create a new action chain and set those values again and other option which i am looking is to directly change the values of the variables through JS and call the action chain again.