I am trying to pass a control's id to a javascript function that adds the value of it(the control which is a textbox) to a listbox but apparently I am not getting it right, can someone please correct me.

Thanks.

<input type=button ID=btnAddtoLstBox value= title=Add this to the list onclick=javascript:addToList(document.getElementById(btnAddtoLstBox));

class=ui-icon ui-icon-refresh ui-corner-all style=width: 20px; height: 20px; background-position: -64px 80px  />



  // scripts to add list items

        function addToList(varTxtBox) {



                 // get the list box

                var lb = document.getElementById(uilstMemTypeTier);



                // get the text to add

                var toAdd = varTxtBox.value;



                if (toAdd == ) return false;



                // look for the delimiter string. if found, alert and do nothing

                if (toAdd.indexOf(delim) != -1) {

                    alert(The value to add to the list cannot contain the text  + delim +  as it is used as the delimiter string.);

                    return false;

                }



                // check if the value is already in the list box

                for (i = 0; i < lb.length; i++) {

                    if (toAdd == lb.options[i].value) {

                        alert(The text you tried to add is already in the list box.);

                        return false;

                    }

                }



                // add it to the hidden field

                document.getElementById(<%=uihdnlistBasedFieldsListItems.ClientID%>).value += toAdd + delim;



                // create an option and add it to the end of the listbox

                lb.options[lb.length] = new Option(toAdd, toAdd);



                // clear the textfield and focus it

                varTxtBox.value = ;

                varTxtBox.focus();

            }