----------- 1234
call toString
String
1234
call valueOf
int
1234
----------- undefined
call toString
String
undefined
call valueOf
int
0
----------- [object Object]
call toString
call valueOf
Error 1050
call valueOf
call toString
Error 1050
--- string null
----------- null
call toString
String
null
call valueOf
int
0
--- normal null
----------- null
call toString
call valueOf
Error 1050
call valueOf
call toString
Error 1050
