[bes]

foo_func=function(){alert("foo")}
bar_func=function(){alert("bar")}
  
name="foo"
call_func=function(){
   window[name+"_func"]()
}
call_func()
name="bar"
call_func()
//  foo
//  bar

упс

(function () {
var foo_func=function(){alert("foo")}
var bar_func=function(){alert("bar")}
  
name="foo"
call_func=function(){
   window[name+"_func"]()
}
call_func()
name="bar"
call_func()
//  foo
//  bar
})();