Radio checked problem in jquery _jquery

It's a very, very, very bad day. Searched for this difficult question for a whole afternoon. To the end, Csdn's friend gave me the right answer, thanks to this friend.

$ ("#ISOK1"). Checked = "Checked";
$ ("#ISOK1"). attr ("Checked", true);
$ ("#Radio1"). attr ("Checked", true);
$ ("#Radio1"). Checked = "Checked";
$ ("#ISOK1") [0].checked = true;

In addition, thanks to another Netizen told me

If you are using jquery1.9 later, attr should not use, to use $ (this). Prop ("checked", true); $ (this). Removeattr ("checked"); Select and remove selected

Thank him, too.