How to position the focus on the linkbutton by pressing Enter in the input? _html/css_WEB-ITnose

The code is as follows:
$( '#password').textbox('textbox' ).keydown(function (e) {
if (e.keyCode == 13) {
$( " #login").linkbutton('linkbutton' ).focus();
                                                                             

                                                                      🎜>                                                                                                   form>                                                                        ;/td>

                                                                                                                                         td>

                                                                                                                 gt;                                                                          usernameObj = document.getElementById("username");
usernameObj.onkeydown = function(event) {

e = event ? event:(window.event ? window.event : null);

// Press When the Enter key is pressed and the input box value is not empty,

if(e.keyCode==13 && usernameObj.value){
document.getElementById("password").focus();
} }
}  
                                                                                                      🎜> $( "#login").linkbutton('linkbutton' ) returns not a jquery object

I guess it should be like this: $( "#login").focus()