How to Swap Two numbers using java script function with one parameter : My Requirement is 
I want to display this output when I gave a(0) the output should come 5 and when I gave a(5) the output should come 0.
a(0) = 5
a(5) = 0
like this 
Hint:
Using this function 
function A(num){} like this

Please Help me how to do this I'm new in JS