document.formName.selectName.options.length=0
document.formName.selectName.options[document.formName.selectName.options.length]=new Option("1","1")
document.formName.selectName.options[document.formName.selectName.options.length]=new Option("1","1")
<%
String list2 = "<option>1</option><option>2</option>.....";
%>