window['string']
this['st5']
(function() { var name = 'strName'; this[name] = 5; alert(window[name]); })();
(function() { var name = 'myvar'; eval(name+'=5'); alert(myvar); })();
(function() { var name = 'aaa'; eval( *!*'var '+*/!* name+'=5'); alert(aaa); // 5 })(); alert( aaa );// not defined