I am aware of this site not working properly. I am working on it!
MooTools
v0.4.6.0 beta
1

I have variable which holds the name of Class (a Mootools Class). How do I create an object of that class using the only the name of the class?

1

Assuming the class was defined in the global scope (the Window scope):

var X='ClassName';
var N=new Window[X](param1,param2...paramN);