evaluate a string expression?

what i'm looking for is something that works like the javascript eval(string) function...

eval(string) takes the string and evaluates it.
example:
var varName = prompt("enter the variable's name that you want to alter.")
var varValue=prompt("enter a value for " + varName)
eval(varName+"=varValue")

is 'variables' a keyword? i think i figured a workaround.

dim variables as new arrayList()
...
...
variables(varName)=varValue

hows that?