Question : undefined error help

help
i am getting an error according to firebug of 'id_con is undefined'.i have made sure all entries are correct and i cannot see how to fix this error. i would be grateful if someone could show me how to correct this error. the error is occuring on this line:

1:	itemlist+= items[i].id_con.substr(3)+",";

many thanks

Attachments:

id-error.txt (2 KB) (File Type Details) 

code file

Answer : undefined error help

@gurvinder372
sorry. might want to give what?

@kryadov
could you do an example based on my code?

many thanks for replies.